….. Although forum software often is reasonable, it doesn’t make me go, “wow”. ….. So, it shouldn’t come as a surprise that when Jeff Atwood, cofounder of Stack Exchange and the author of the famous “Coding Horror” blog, announced he was going to make better Web-based forum software, I personally reacted with a shrug. After all, I’ve used and seen forum software for years. How much different or better could it be?
Well, I can report to you that even though Discourse, Atwood’s open-source forum software, is still somewhat unfinished, it already is head and shoulders above other forums I have used, as both a user and an administrator. The fact that it is open source, based on Ruby, PostgreSQL and Ember.js is icing on the cake, making what already was excellent software even better. …..
This afternoon our Twitter stream informed us of the existence of this thing: An Expansion Board Made for Raspberry Pi made by a company called SupTronics, which appears to be headquartered in Shenzhen, China. It can be purchased from this site, and the specifications can be found here. Quoting from that page:
Introduction
The X100 expansion board designed for use on the Raspberry Pi (RPi) computer platform. The board supplies RPi with a regulated +5V from a wide-range voltage source and also contains a real-time clock, a RS232 master port, a HDMI to VGA converter, 3-port USB hub, memory card reader, and 8-channel darlington Driver.
Main Features
Exactly same size as Raspberry Pi (85 x 56mm)
Directly installed into the GPIO header pins with no wiring or soldering
6-23V input to 5V, 3A high-efficiency step-down DC/DC converter to supply your RPI
Supports HDMI to VGA (NOT powered by the RPI’s HDMI port)
Supports self-powered USB hub (Total 4 ports available)
Supports self-powered SD and Micro-SD card reader
RTC based on NXP PCF2127AT / PCF2129AT with CR2032 backup battery
RS232 Serial Port
Having the reset switch convenient to enable RPi reset facility
Having two slots to make use of RPi’s FPC connector (S1 & S5)
Allowing to stack along with other expansion boards.
8-channel darlington Driver chip allowing to control electronic circuits which require more current to drive them
Have DIP switch to remove connection from RPi’s pin header so as to keep using other expansion board with no effect.
* This expanson board is suitable for Raspberry Pi Rev 2 Model B.
We haven’t actually had our hands on the device, but our initial impression is that it adds a bunch of things that might each be individually interesting to a certain subset of Raspberry Pi owners, but in most cases it will be priced too high to get that one feature you really need, and if you only need one of those features you can probably build it yourself or find a cheaper way to add it. Let’s take each actual feature in turn:
6-23V input to 5V, 3A high-efficiency step-down DC/DC converter to supply your RPI
This in and of itself is great if it works, since the Raspberry Pi is notoriously finicky about power supplies (use one that’s not quite stable enough and you’re likely to have occasional SD card corruption). But a good power supply wouldn’t cost nearly this much. However, if you want to install a Raspberry Pi in a vehicle that only has a 12 volt supply available, or some other situation where the available power is unstable, then this become a more desirable feature.
Supports HDMI to VGA
WHY? Who uses VGA anymore? Oh, right, this came out of China, where the first world dumps all its CRT monitors that nobody wants anymore. We’d have much rather seen this relatively ginormous space used to provide improved audio capability; perhaps a S/PDIF connector supporting full 5.1 or even 7.1 audio. That would have been something we could actually make use of. And why do they use the word “Supports” to mean “This is included on the board”?
Supports self-powered USB hub (Total 4 ports available)
It appears this means that it includes 4 USB ports. Which is great if you need them, but you can buy powered USB hubs for less than what this costs.
Supports self-powered SD and Micro-SD card reader
Again this is a rather strange way to word this, because the card reader is on the board. Since the Raspberry Pi already has a SD card slot, what’s the advantage of having one on this board? For many users there will be none.
RTC based on NXP PCF2127AT / PCF2129AT with CR2032 backup battery
This is really only useful if you are using your Raspberry Pi in a situation where you can’t update the time from an Internet-based timeserver. And even then, it only matters if keeping something close to the exact time is important to your application. Again, we could see this being most useful in a vehicle-based application.
RS232 Serial Port
This is so early 2000’s. A rare few people might have a use for this (and for those that do, we suspect that add-on serial port circuits are available for less than this) but for most people this is just a useless port that wastes space that could have been occupied by something useful, like maybe a Wi-Fi or Bluetooth module, or any of a number of things that might actually be useful to people in this decade.
Having the reset switch convenient to enable RPi reset facility
A switch that costs less than a dollar to add is hardly a reason to buy this board, but at least it’s more useful than some of the other things they put on here. But, why not a true power switch, that (when used with some software) would do a proper shutdown on the Raspberry Pi? That would have been far more useful. And, viewed one way, giving people easier access to a cold reset is not such a great idea, since every time you use it you risk corrupting your SD card. Yet we understand that it can be a convenient feature if the Raspberry Pi is prone to freezing up occasionally.
8-channel darlington Driver chip allowing to control electronic circuits which require more current to drive them
This appears to be basically a ULN2803A integrated circuit with the outputs brought out to some inconvenient connectors. It’s described this way:
ULN2803 8-channel RC servo port
Bring in some muscle to your output pins with 8 mighty Darlingtons! This driver chip contains 8 drivers that can sink 500mA from a selecable 5V or input voltage supply and has kickback diodes included inside for driving coils. This will let your little microcontroller or microcomputer power solenoids, DC motors (in one direction) and unipolar stepper motors. The GPIO Pins are connected to ULN2803 inputs through a DIP switch, with the its outputs going to two array of Wire-to-Board header. Alternatively, these ports can be used to supply +5V or input voltage to other external circuitry, or embedded devices.Please note that this is an ‘open collector’ driver – it can only be used to connect the load to ground and there will be a 1 Volt (or more) ‘drop’ across the internal transistors.
For some people this might be the most useful thing on this board, although it would be nice if there were better documentation on how it’s used. It appears that this converts the Raspberry Pi GPIO ports to make them behave more like those on an Arduino, though we can’t be entirely sure. But you can do the pretty much the same thing same thing with a cheap breadboard, a ULN2803A (get the kind with long pins, not the surface mount type), some connector wires, and an external power supply. Here you get all that in one package (except you will still need the external power supply), but why on earth did they add those funky little white GPIO connectors on the board? We realize those appear to be similar to the type used to bring power to certain devices (such as some internal drives) but still, the plugs that fit those connectors are not something that the average person is likely to have lying around.
Basically, it’s our opinion, again based solely on the information we can find online, that this will only be a good fit for people that happen to need several of these features, or that simply have money to burn and no inclination to look for other ways to achieve the same results. And (at least in the first world) relatively few people will have use for a VGA port, and probably even fewer for a serial port. We can see some of the other features being a bit more useful, particularly in vehicle based and remote sensing applications, or cases where you plan to power this off a solar or wind-powered source of electricity.
If there is ever a second revision on this board, we would recommend the following:
– Ditch the VGA port and replace it with a S/PDIF audio output.
– Ditch the serial port and consider replacing it with a wi-fi and/or bluetooth connection
– Change the reset button so that it becomes a true power on/off button, so that when the power is turned off it signals the Raspberry Pi to do a graceful shutdown (the equivalent of typing sudo poweroff at the command prompt) and then waits for that shutdown to complete before removing the power. We would expect that you’d need to run a background task to catch the shutdown signal and run the shutdown sequence, but you have to install additional software to make the RTC work, so this would simply be similar to that procedure. And several people have built standalone devices that do this, so it’s definitely possible, and this would be far better than giving a typical user an easy way to do a “cold” reset that might bork their system.
– Add a receiver for an infrared remote (suggested by Jeff Darlington in the comments section)
We neither recommend this board nor advise against it, we’re just saying that depending on the reasons you’d want to use it, there might be better or less expensive options. But if you can utilize several of the functions on this board, then it might be a good value for you, assuming that it works as advertised and that if you plan to use the GPIO connections, you can actually figure out how you’re supposed to connect to them.
This started out as a simple link to an installation tutorial that we found:
Now days Android is leading mobile operating system , there are wide range of app and games in android , If you are really fond of using android applications but unfortunately you don’t have any android supported Phone. Then don’t worry you can still enjoy all the Android application and Games on your PC and Laptop, One software will helps you to make your dream come true. Now days Bluestacks is one of the famous and working Software Which convert any android apps in Windows or Mac version. By using Bluestacks software you can run easily any android app on your pc or laptop.
In addition to the Windows versions, there is also a Mac version of the Bluestacks software, and that’s what we tried. But as soon as you install it and attempt to run it, to comes up with an error message that reads:
“Network Issue. The network is experiencing some problem. Please retry or cancel.”
Well, this bug still exists, and it stops you cold after you have installed the software. So for now, Bluestacks earns our “avoid this software package” designation. Don’t waste a minute of your life trying to install and run this thing, because several users with more experience than us have apparently tried and failed. But if you ignore our advice and somehow manage to get it working, please leave a comment telling us how you did it!
EDIT: In the meantime, here’s another way to run Android on your PC or Mac, though we haven’t actually tried this one yet:
This is an edited version of a post that originally appeared on a blog called The Michigan Telephone Blog, which was written by a friend before he decided to stop blogging. It is reposted with his permission. Comments dated before the year 2013 were originally posted to his blog. In order to comply with Federal Trade Commission regulations, I am disclosing that he received a free product sample of the item under review prior to writing the review, and that any links to Amazon.com in this article are affiliate links, and if you make a purchase through one of those links I will receive a small commission on the sale.
The FreeSWITCH Cookbook is the second book from Packt Publishing on the subject of FreeSWITCH, which in my opinion may someday soon be the “telephony software engine” that replaces Asterisk in popularity. I’ve previously reviewed the earlier book, FreeSWITCH 1.0.6, and this book builds on that one. If you know nothing at all about FreeSWITCH, you’ll probably want to start with the earlier book, because it gives you all the basics. The publisher was kind enough to send me a complementary copy of the new book for review purposes.
This book, as the name implies, is a “cookbook” in that it gives “recipes” for how to do certain tasks. Just as an actual cookbook presupposes certain knowledge (that you know how to operate an oven; the difference between certain measuring units, etc.) this book tends to start with the assumption that you already have a grasp of how to set up FreeSWITCH, but you may need examples of the configuration necessary to perform certain tasks. And, that’s what this book gives you. The idea, I think, is that if even one of the “recipes” saves you a couple of hours of head-scratching and trying to figure out how to do something, then that justifies the cost of the book.
Normally in this type of review I would list the chapters, but in the case of this book you’ll probably want to know what’s in each chapter. So, here is the complete Table of Contents from the Packt Publishing web site:
Launching a call with an inbound event socket connection
Using the ESL connection object for call control
Using the built-in web interface
Chapter 5: PBX Functionality
Introduction
Creating users
Accessing voicemail
Company directory
Using phrase macros to build sound prompts
Creating XML IVR menus
Music on hold
Creating conferences
Sending faxes
Receiving faxes
Basic text-to-speech with mod_flite
Advanced text-to-speech with mod_tts_commandline
Listening to live calls with telecast
Recording calls
Index
As you can see, the order progresses from the basics (setting up your extensions, and inbound and outbound routing) to the sort of things you might want to do in a more full-featured PBX. Chapter 4 in particular will be of interest to many developers. I’ll quote from the introduction to that chapter:
One of the most powerful features of FreeSWITCH is the ability to connect to it and control it from an external resource. This is made possible by the powerful FreeSWITCH event system and its connection to the outside world: the event socket. The event socket interface is a simple TCP-based connection that programmers can use to connect to the inner-workings of a FreeSWITCH server. Furthermore, the FreeSWITCH developers have also created the Event Socket Library (ESL), which is an abstraction layer to make programming with the event socket a lot simpler. The following languages are supported by ESL:
C/C++
Lua
Perl
PHP
Python
Ruby
TCL
Keep in mind that the ESL is only an abstraction library—you can connect to the event socket with any socket-capable application, including telnet!
The tips in this chapter will focus most of their attention on using the event socket for some common use cases. The last tip, though, will introduce a particularly interesting way to connect to FreeSWITCH externally without using the event socket, namely, using the built-in web server that is enabled when you install mod_xml_rpc. Regardless of how you wish to control FreeSWITCH, it is highly recommended that you read the first recipe in this chapter, Getting familiar with the fs_cli interface, as this will serve you well in all aspects of working with FreeSWITCH.
This, of course, is somewhat analogous to controlling Asterisk via Asterisk Gateway Interface programming, but it appears that you get more functionality in FreeSWITCH, and more languages are supported.
I have said on many occasions that I am not a programmer, so in one sense I’m not exactly the target audience for this book. However, I know just enough about coding to be able to appreciate when a book lays out examples in a clear, easy-to-understand manner, with enough comments for you to “get” what the author is trying to explain to you. Personally, if I could just get over my hurdle of not fully grasping XML (which is actually strange, because I have no problem understanding basic HTML, which is very similar), I think that this book would be a lot more useful to me in understanding how to do things in FreeSWITCH. I sort of “get” Asterisk dialplans a little bit, but for some odd reason XML is not nearly as understandable to me. I guess everyone’s mind works a little differently. If you work with FreeSWITCH and you don’t share my mental block with regard to XML, you are really going to like this book. In terms of layout and readability, I think it’s one of the best titles I’ve seen from Packt.
One thing in particular I like about this book is that they don’t just give you the XML dialplan (although the XML is included), but the authors then explain to you how it works. In addition, in many cases they also give you additional related information, such as tweaks you can make to the XML to perform slightly different functions or otherwise modify the behavior, and links to additional resources you made need. So, you are not just viewing XML samples and then left on your own to puzzle out how they work!
In fact, I really only have one criticism of the book — it’s too short! It’s only 134 pages from opening material to the index at the end. But I’ll balance that by saying this — I’ve seen too many books that have a high page count, but a high percentage of the book is “filler”, much like the low-grade ground beef you buy at some supermarkets. With this book, other than a few obligatory opening pages that tell you a bit about the authors and others involved with the book, it’s solid content. No history of something or other, no long personal ramblings by the authors, etc. — just the “recipes” for doing the various things you might want to do in FreeSWITCH, and then the explanations as to how they work and other useful and relevant content. You have to ask yourself the question, “Will this book save me time?” (almost certainly, if you are doing any of the things covered in the chapters of this book) and “How much is my time worth?”, and “Can I learn something from this book that would be useful to me?” (if you developing a project using FreeSWITCH, I can’t imagine how you wouldn’t).
My personal hope is that those who write, or who may be considering writing the next generation of GUI configuration programs for FreeSWITCH will get this book. It basically shows you how to do everything you need to do to create a working PBX, and for those that are programmers, Chapter 4 is where the real magic is revealed. That said, I would highly recommend this book for anyone attempting to develop a project using FreeSWITCH!
This is an edited version of a post that originally appeared on a blog called The Michigan Telephone Blog, which was written by a friend before he decided to stop blogging. It is reposted with his permission. Comments dated before the year 2013 were originally posted to his blog. In order to comply with Federal Trade Commission regulations, I am disclosing that he received a free product sample of the item under review prior to writing the review, and that any links to Amazon.com in this article are affiliate links, and if you make a purchase through one of those links I will receive a small commission on the sale.
Cover of FreeSWITCH 1.0.6
In case you’ve never heard of FreeSWITCH, it is a “telephony software engine”, which means it’s in the same category as Asterisk. Over the years I’ve noticed that some Asterisk users have become frustrated with Asterisk due to unfixed bugs and design flaws that mean that the software doesn’t always work as it should. So, for quite some time, I’d hoped that a viable alternative to Asterisk might emerge, if only to keep the Asterisk developers on their toes. Competition between software projects tends to be a healthy thing, and from what I’ve read in this book, it appears that FreeSWITCH just may be the software product that eventually replaces Asterisk as the #1 open source telephony software engine.
Before I begin, as is my custom with such reviews, let’s start with a quick overview of what’s in each chapter (for the complete Table of Contents, see the Packt Publishing web site):
Preface
Chapter 1: Architecture of FreeSWITCH – includes notes on the FreeSWITCH design and important modules
Chapter 2: Building and Installation – how to build and run FreeSWITCH under Linux/Unix, Mac OS X, or Windows
Chapter 3: Test Driving the Default Configuration – here you learn how to control FreeSWITCH with the CLI and to make your first call
Chapter 4: SIP and the User Directory – includes adding users, setting up voicemail, and setting up a gateway to connect to the world (link is to sample chapter in PDF format at the Packt Publishing site)
Chapter 5: Understanding the XML Dialplan – this gets into the “meat” of FreeSWITCH dialplan creation
Chapter 6: Using the Built-in XML IVR Engine – here’s where you learn one way to build an IVR (auto-attendant)
Chapter 7: Building IVR Applications with Lua – really an example of using a scripting language with FreeSWITCH. A few other languages are supported
Chapter 8: Advanced Dialplan Concepts – if Chapter 5 was the hamburger, this is the sirloin
Chapter 9: Controlling FreeSWITCH Externally – explains the event system architecture, and how to read and send events
Chapter 10: Advanced Features and Further Reading – includes multi-user conferencing, billing, XML/Curl, alternative endpoints, and configuration tools and related projects
Set up a basic system to make and receive phone calls, make calls between extensions, and utilize basic PBX functionality
Avoid common implementation mistakes and deploy various features of this telephony system with best practices and expert tips
Perform routine maintenance for smooth running and troubleshoot the system when things are not going right
Apply regular expressions to unlock unique and powerful call routing scenarios
Call your own application(s) when particular events occur and control FreeSWITCH using the powerful Event Socket
Set up multi-party conferencing facilities for your system
Interact with callers, gather information, and route calls to the appropriate recipient using the automated, built-in XML IVR (Interactive Voice Response) engine
Create a flexible dialplan, and allow third-party tools to be quickly and easily created using dialplan parsers other than the default XML Dialplan
Park multiple calls in a FIFO queue and unpark them in the order in which they were received, using the mod_fifo module
Record an entire phone call or session using the call recording feature
Create advanced call control applications with the Lua scripting language
Take a peek into the vibrant online community and history of FreeSWITCH
Approach
This book is a step-by-step tutorial with clear instructions and screenshots to guide you through the creation of a complete, cost-effective telephony system. You will start with installation, walk through the different features, and see how to manage and maintain the system.
Who this book is written for
If you are an IT professional or enthusiast who is interested in quickly getting a powerful telephony system up and running using the free and open source application FreeSWITCH, this book is for you. Telephony experience will be helpful, but is not required.
Now, here are my impressions. Please bear in mind that I did not actually attempt to build a working FreeSWITCH installation (I would need yet another spare computer to do that), but I certainly feel as though I could after reading this book. One thing that is somewhat uncommon about this book is that the author of the software is also one of the authors of the book. Too often, when you see a book written about a piece of software, the writer doesn’t fully understand the software and therefore makes guesses and assumptions about how it works, that may lead to problems down the road if you follow their advice. When the software author collaborates on the book, that’s far less likely to happen, and indeed, at no point in this book did I get the feeling that the author was struggling to understand the subject. I will even go so far as to say that this is one of the best written technical books I have read in a long time.
The biggest complaint I had about this book — and it is a very minor one — is that it could have benefited from another proofreader. Occasionally I’d see an obvious error that the proofreader should have caught — nothing major, and nothing I couldn’t figure out with about two seconds of thought, with one exception. On page 91 of the book, it appears to me as though there is some missing text at the bottom of the page. It’s discussing making a test call to Music on Hold and then, suddenly and jarringly, it jumps into a time of day example. I think the disconnect occurs in middle of a sentence: “In our example, call the debug output is as follows:” The sentence as written does not make sense to me, and it appears a block of text (perhaps a large one) may have been omitted at this point. But that is the only place in the book where I encountered an error of that magnitude. I have submitted the error to Packt Publishing and I’m hoping they will figure out what was supposed to go there and place it in the errata section of their web site.
One other point I will make about a software author writing a book on his own creation is that I think sometimes, it’s difficult for the author to correctly envision how end users will want to use the software. As an example, virtually all the dialplan examples in this book are in XML. There may be advantages to using XML, but it’s not going to be very familiar to someone coming from an Asterisk background, and I might have wished for a few non-XML examples. On pages 158-159, the author notes that,
There is a common misconception that the FreeSWITCH Dialplan is based on, and requires, XML. That is simply not true. If you prefer flat files, you could use them to store your Dialplan configuration. If you prefer YAML, you could use that, too. You just need to load the correct C-based Dialplan module to interpret your stored logic for the particular type of configuration file you want FreeSWITCH to utilize.
This aside, the most common (and currently, the most robust) Dialplan processing mechanism in FreeSWITCH is still the XML-based Dialplan module. Most Dialplan examples that are shipped with FreeSWITCH, or those scattered on the Web are in XML, therefore, they will remain the focus of this chapter. …..
Indeed, there is even an Asterisk dialplan module, albeit with limited capabilities. From page 199:
If you are used to the Asterisk Dialplan, some basic functionality is provided by the Asterisk Dialplan module, although it is not nearly as feature-rich as the XML engine. You can process contexts and route calls to phones using the Asterisk Dialplan. This module, again, is more of a sample on how to build an alternate Dialplan processing module and should not be utilized as a full, feature-rich Dialplan system.
Yet you won’t find examples using flat files, YAML, or Asterisk Dialplan in the book. However, the XML examples were clearly written and easy to understand, so I don’t think that there would be a steep learning curve to start writing dialplans in XML, assuming you are a proficient enough coder to write dialplans in the first place. And, I suspect that XML would be easier for a new user to pick up than any of the other options.
I mention the above to emphasize two points: FreeSWITCH is different from Asterisk. If you are thinking about moving from Asterisk to FreeSWITCH, you need this book to get you up to speed on the differences. And second, FreeSWITCH is both more capable than Asterisk, and arguably easier to use, once you get used to the differences (or if you have no prior experience with similar software). FreeSWITCH appears to have been designed from the ground up to avoid the issues that have plagued Asterisk, particularly those that cause Asterisk to fall to its knees under heavy load or heavy call volumes. Even if you’re a long-time Asterisk user, you may want to get this book just to see what you’re missing. You might decide that it’s worth your effort to set up a test system using FreeSWITCH, to help you understand how much better the next generation of telephony software engines can be.
One other point, in case you are reading this review several months after I wrote it — the author notes this in the preface:
At the time of this writing this book, the FreeSWITCH developers were putting the finishing touches on FreeSWITCH version 1.2. While the examples presented in this book were specifically tested with version 1.0.6, they have also been confirmed to work with the latest FreeSWITCH development versions that form the basis of version 1.2. Do not be concerned about the fact that this material does not cover version 1.2—it certainly does. The FreeSWITCH user interface is very stable between versions; therefore, this text will be applicable for years to come.
There will no doubt be some of you who are reading this that wonder if there are any Web GUI “front ends” (dialplan and configuration file generators) for FreeSWITCH. Indeed there are, and they are covered in Chapter 10, which briefly explains the differences between WikiPBX, FreePBX v3, FusionPBX, and 2600hz. Even if you plan on using a Web GUI, there may be times when you find the need to write a bit of custom code, and in that case having this book available would definitely be helpful to you.
One other thing I personally found interesting in this book was Appendix B, “The History Of FreeSWITCH.” This explains how FreeSWITCH came to be, and along the way offers further explanation on how it is different from Asterisk and why the developers felt the need to start a new project. What I think I found most interesting (and perhaps unfortunate, depending on your point of view) is that FreeSWITCH could have been the basis for Asterisk version 2, had only the Asterisk developers reacted positively to the idea. I see this sort of thing happen occasionally in the open source community, where the lead developers of a project start to develop an attitude that does not encourage outside contributions (or, they treat contributions or suggestions for improvement as if they were piles of steaming dog poo on their doorstep). Perhaps this should serve as a cautionary tale to such developers that your project can always be replaced by something better, if you do not encourage contributions to your own project from those not currently in your “inner circle” of developers.
As you may know if you have read my previous reviews, it’s rare that I get wildly enthusiastic about a book. In this case I’ll make an exception, because overall the book is that well-written (my comments above notwithstanding). If you have any interest at all in using FreeSWITCH, or are even just curious about it, you really should buy this book. It’s available in both traditional softcover dead-tree format, and as a DRM free Adobe PDF eBook, and there’s even a package deal if you want both formats. Don’t forget that you can view a sample chapter (PDF format) prior to purchase. EDIT: Also, there is an online article by the book’s authors entitled FreeSWITCH: Utilizing the Built-in IVR Engine.
This is an edited version of a post that originally appeared on a blog called The Michigan Telephone Blog, which was written by a friend before he decided to stop blogging. It is reposted with his permission. Comments dated before the year 2013 were originally posted to his blog.
This article was originally posted in June, 2010.
I recently had the experience of trying to help someone make a Sangoma USBfxo device (model U100) work on a server that runs FreePBX and Asterisk. The advertised features of this device are as follows:
Dual FXO ports
Easy installation, no need to open up computer to install PCI/PCIe card
Supports up to 2 simultaneous calls
Compact plastic enclosure
Low power consumption, takes power from USB bus
USB 2.0 compliant (compatible with USB 1.1)
The first thing I would note is that although you don’t have to open up the computer, it’s definitely not “plug and play.” At the very least you have to install driver software, and on an Asterisk server you will also need to install and configure DADHI or ZAPTEL (unless this has already been done). Depending on your level of expertise, this might be easy, or quite daunting. I would certainly take issue with the claim of “easy installation” although I can understand how a true Linux geek might consider it a walk in the park. It wasn’t so much that there were any major hitches in the installation as that it was time consuming and required quite a bit of mental effort to figure out what needed to be done — someone who has just set up a PBX using a “load and go” distribution like Elastix, PBX in a Flash, AsteriskNOW, Trixbox, etc. might not find it all that easy to get this thing working.
The major issue we had was with the performance. We initially discovered that it was “clipping” speech severely, causing audio artifacts that are difficult to describe in print, but unpleasant to hear. We got in touch with Sangoma customer support and finally traced the problem to the built in hardware echo cancellation. By disabling the hardware echo cancellation, the speech was clear, but of course we then had mild echo. Enabling echo cancellation in Zaptel fixed that on a temporary basis, but about a week later Sangoma customer support e-mailed us and suggested that we try OSLEC, the open source echo canceler. We might have actually done that had we not discovered another issue in the meantime, that made us decide we didn’t want to mess with this unit anymore.
This new issue was that initially, it did not pick up incoming caller ID on incoming calls. We discovered that this could be fixed by changing the gain settings in Zaptel, but even when we did that it still wasn’t 100% reliable (I’d say it worked about 90% of the time). And, the downside of that was that we had to reduce the incoming gain, so that it was harder to hear callers.
We’ve used Sipura SPA-3000’s before for this same function, although they are only single line units (they have one FXS port and one FXO port) and have never had any of these issues. The main reason we tried the USBfxo was because we wanted two FXO ports, and also liked the idea that it was powered off the USB cable, and didn’t require us to have yet another device with a “wall wart” to plug in. But the difficulties with Caller ID, volume levels, and the fact that Sangoma had apparently given up on getting the hardware echo cancellation to work without distorting the audio led us to get frustrated with this device fairly quickly. The non-techies that had to make and receive calls that went through this device were not very understanding of the issues, especially since the SPA-3000’s (now superseded by the Linksys SPA-3102, which is essentially an updated version of the Sipura SPA-3000) had always worked much more reliably. We finally gave in and found another Sipura SPA-3000 on eBay and put it into service, and within a relatively short time (part of which was spent locating and installing updated firmware) it was working like a champ. Unlike the Sangoma, it detects the Caller ID 100% of the time, and we can tweak the transmit and receive gain to comfortable levels.
My personal opinion is that Sangoma should be ashamed to put their name on the USBfxo. The hardware echo cancellation, in a word, sucks. And one of the big reasons you’d buy a brand like Sangoma in the first place is because of the supposedly superior echo cancellation. Echo cancellation is supposed to cancel echo, not make it sound like your words are clipped. My guess is that the hardware echo cancellation is far too aggressive and they don’t give you any way to “tune” it — you can either enable or disable it, but that’s all. The USBfxo is a great idea, but it needs to go back to the drawing board. Sangoma’s motto (shown on their Wiki pages, etc.) is “Because it must work!”, but apparently that motto does not imply that it must work well!
Also, a note to Sangoma customer service — next time a customer is dropping hints that they’d like you to take your defective unit back and send a replacement, you might want to be a bit more responsive to that request. We were willing to work with you up to a point but the message came through loud and clear that you really didn’t want to replace this dog of a device unless you absolutely had to. We didn’t sign up to be beta testers, we just wanted the damn thing to work. Given Sangoma’s (perhaps undeserved) reputation we really thought you’d be more agreeable to making sure that we got a unit that worked, not making us try a bunch of different things and then ultimately told to try OSLEC, effectively giving up hope that the hardware echo cancellation would ever work properly.
Another suggestion to Sangoma (or any other manufacturer that may be listening) — most of us who did not cut our teeth on Linux would probably prefer not to have to mess with ZAPTEL or DADHI. The nice thing about the Linksys/Sipura devices is that they sit out on the network and appear as just another SIP-based device, and in FreePBX you configure them pretty much as you would any other SIP trunk. I’m not saying that installing any of these devices is the proverbial “piece of cake”, especially if you have never done it before, but when you have to start installing and configuring drivers, that goes outside of the realm of what I would consider easy to install. What someone really needs to come out with is an inexpensive four to six-port SIP based FXO device that sits out on your local network, like the SPA-3000/3102.
If you are in need of one or two FXO ports for your Asterisk server, my advice would be to first try one or two Sipura SPA-3000 or Linksys SPA-3102 devices (following these instructions if you are a FreePBX user) — if those do not work the way you’d like, you can always resell them on eBay and then try a more expensive solution. If your server doesn’t have card slots (as is increasingly the case, as users turn to small computers like the Acer Aspire Revo to use as small, power-efficient PBX’s) then your choices are limited to external devices such as the aformentioned units. However, if your system can accept internal cards, then you can buy cards that provide FXO ports from several manufacturers, including Digium and Sangoma (if you need eight or more FXO ports than I believe there are other external options, but they are quite a bit more pricey and I have not really investigated them, so I won’t comment on them at this point. However, if any manufacturer would care to send a review sample, I’d be more than happy to give it a try!). 😉
The one caveat I will add is that not every device will work on every line. If you have a very long line from a traditional telephone company, your requirements (and experience with a particular device) may be quite different from someone who is sitting 500 feet from the central office, or someone who’s trying to take the output of a cable company’s VoIP adapter and pipe it over to the FXO card or device using twenty feet of copper wire. Just because the Sipura devices have worked better for us does not mean they will for you. I’m guessing that some people have purchased the exact same Sangoma device that we tried and were able to get it working well enough for their needs, but I just cannot recommend this device — at least not until Sangoma fixes the echo cancellation, and makes it read the incoming Caller ID reliably 100% of the time, preferably without having to change the incoming gain in DADHI or ZAPTEL.
This is an edited version of a post that originally appeared on a blog called The Michigan Telephone Blog, which was written by a friend before he decided to stop blogging. It is reposted with his permission. Comments dated before the year 2013 were originally posted to his blog. In order to comply with Federal Trade Commission regulations, I am disclosing that he received a free product sample of the item under review prior to writing the review, and that any links to Amazon.com in this article are affiliate links, and if you make a purchase through one of those links I will receive a small commission on the sale.
Here’s what the publisher wants you to know about the book (my comments will follow):
In Detail
OpenVPN is a powerful, open source SSL VPN application. It can secure site-to-site connections, WiFi, and enterprise-scale remote connections. While being a full-featured VPN solution, OpenVPN is easy to use and does not suffer from the complexity that characterizes other IPsec VPN implementations. It uses the secure and stable TLS/SSL mechanisms for authentication and encryption. This book is an easy introduction to this popular VPN application. After introducing the basics of security and VPN, it moves on to cover using OpenVPN, from installing it on various platforms, through configuring basic tunnels, to more advanced features, such as using the application with firewalls, routers, proxy servers, and OpenVPN scripting.
This is a practical guide to using OpenVPN for building both basic and complex Virtual Private Networks. It will save you a lot of time and help you build better VPNs that suit your requirements. While providing only necessary theoretical background, the book takes a practical approach, presenting plenty of examples. It starts with an introduction into the theory of VPNs and OpenVPN, followed by a simple installation example on almost every available platform. After a concise and ordered list of OpenVPN’s parameters, we dive into connecting several machines in a safe way. The last third of the book deals with professional and high-end scenarios, and also mobile integration. After having read the whole book and followed and understood all the examples, you will be an expert in VPN, Security, and especially in OpenVPN Technology. This book was written for version 2.0.9 of OpenVPN, but all examples have been tested and run smoothly on version 2.1 too. Read the full Table of Contents for Beginning OpenVPN 2.0.9
What you will learn from this book
Install OpenVPN on Windows Server, Vista, and Mac OS X and also on different Linux versions and FreeBSD
Learn basic security concepts necessary to understand VPNs and OpenVPN in particular
Take a look at encryption matters, symmetric and asymmetric keying, and certificates
Connect Windows and Linux systems and safely transfer the necessary encryption keys using WinSCP
Learn about OpenVPN, its development, features, resources, advantages, and disadvantages compared to other VPN solutions, especially IPsec
Discuss non-standard and advanced methods of installing OpenVPN by compiling the source code provided by the OpenVPN project
Create an encryption key for OpenVPN and use it to set up an OpenVPN tunnel between two Windows systems in the same network
Create X.509 server and client certificates for use with OpenVPN and learn how to use tools to debug and monitor VPN tunnels
Create and administer certificates that have to be transferred to the machines that are supposed to take part in the VPN
Configure two different firewall networks that connect to each other through the secure OpenVPN tunnel
Install and use XCA and TinyCA2 to generate certificate revocation lists that are used to block unwanted connections by formerly authorized clients
Install OpenVPN on Windows Mobile and Smartphones running embedded Linux, like Nokia’s Maemo platform
Analyze the flow of datagrams between the VPN servers and the connected networks with tools like ifconfig, ping, traceroute, and mtr
Approach
This book is an easy introduction to OpenVPN. While providing only necessary theoretical background, it takes a practical approach, presenting plenty of examples. It is written in a friendly style making this complex topic easy and a joy to read. It first covers basic VPN concepts, then moves to introduce basic OpenVPN configurations, before covering advanced uses of OpenVPN.
Who this book is written for
This book is for both experienced and new OpenVPN users. If you are interested in security and privacy in the internet, or want to have your notebook or mobile phone connected safely to the internet, the server in your company, or at home, you will find this book useful. It presumes basic knowledge of Linux, but no knowledge of VPNs is required.
Now back to my mini-review. If you read my original review (which explains why I think a VPN can be an important part of securing private VoIP networks, among other uses), you know that I found Mr. Feilner’s original book quite helpful in giving me a grasp on VPNs, a subject I’d known very little about prior to that point. There were a few things I thought could have been covered better, though, so I was interested to see if those things had been addressed in this updated edition.
As I had more or less noted, the author seemed to slightly prefer SuSE Linux over other versions of Linux, and the Shorewall firewall over other Linux firewall solutions, and (in my opinion) the new book still uses more pages than are really necessary talking about how to set up and configure Shorewall, but at least now the authors do provide some minimal information about the far more popular iptables firewall tool (a little over three pages). It would have been nice to see a more in-depth treatment of this subject, because sometimes setting up iptables correctly is one key to getting your VPN to work as you want it to, particularly if you need or want to do anything more complicated than a simple VPN tunnel. It’s a minor nit, to be sure, because there’s plenty of information on the web about how to set up and configure iptables, but I personally would have given that topic more than three pages.
Then I discovered they’d made one addition that I really wanted to see: A totally new chapter on OpenVPN GUI tools, and in particular, a section on Webmin’s OpenVPN plugin. My disappointment again was that this was not a more exhaustive treatment of the subject. Actually, it’s little more than a mention that the plugin exists, and a few screenshots. Granted that this was more than appeared in the original volume, and just informing readers of the existence of that plugin is no small thing, but when I did my series on Setting up an OpenVPN tunnel using a CentOS-based system as the server and a router flashed with Tomato firmware as the client, it took me twoparts to explain how to configure the Webmin plugin. That same chapter also talks about some client GUI’s for Linux, but doesn’t spend more than a page or two on any of them.
I’m not really faulting the authors here — it’s very apparent that they write about what they know, and they definitely know their stuff when it comes to OpenVPN, whereas they may not be quite as familiar with Webmin or iptables. That said, Windows users should find all the information they need to set up an OpenVPN tunnel and then some, and Linux newbies get enough information to at least point them in the right direction. As for Mac users, the coverage there is about the same as in the previous edition, which is to say that there’s about three pages on how to install Tunnelblick. However, much of the information in the book is not OS specific, and those with some experience with Linux or OS X should have no trouble at all following along.
On a positive note, there are many examples and screenshots in the book, and in this one the screenshots are actually readable (well, I did need my reading glasses for a few of them, but then I’m getting to the point where I need my reading glasses to read the cooking directions on a frozen dinner!). And, the authors’ writing style is clear and easy to understand. Also, there’s a totally new (albeit relatively short) chapter on Mobile Security, which may be of interest to some of the “road warriors” out there.
So, my recommendation is this: If you read Markus Feilner’s previous book on OpenVPN and liked it, you’re almost certainly going to want to read this one, just to get up to date. If you didn’t read the previous edition but just want to get up to speed on OpenVPN, this really is one of the better books on the subject, provided that you understand that at times you may have to supplement the book with a bit of additional research on the Web, particularly if you are running OS X or Linux as your operating system (but at least you’ll have a much better handle on topics for additional research).
The reason this is a mini-review and not a full review is because due to personal/family issues I haven’t had time to do much more than skim through the new book, rather than give it a complete read as I normally prefer to do. But since Packt Publishing kindly sent me the book over a month ago, I feel as though it’s a disservice to both them and to the readers of this blog to delay mentioning it any longer. Despite my comments about the paucity of additional pages on the particular topics I’d hoped to read more about, this is still a great book for those who need to set up and secure an OpenVPN tunnel, particularly if you’re just starting out and know next to nothing about VPNs and/or OpenVPN.
This is an edited version of a post that originally appeared on a blog called The Michigan Telephone Blog, which was written by a friend before he decided to stop blogging. It is reposted with his permission. Comments dated before the year 2013 were originally posted to his blog. In order to comply with Federal Trade Commission regulations, I am disclosing that he received a free product sample of the item under review prior to writing the review, and that any links to Amazon.com in this article are affiliate links, and if you make a purchase through one of those links I will receive a small commission on the sale.
This article was originally published in December, 2009.
Cover of Building Enterprise Ready Telephony Systems with sipXecs 4.0
Regular readers of this blog may recall that I recently reviewed another Packt Publishing book, FreePBX 2.5 Powerful Telephony Solutions by Alex Robar, and that my review was generally positive. However, I have wondered for a while if there was going to be any serious competition for Asterisk and FreePBX that would also be open source, and freely available to anyone that cares to download it. Well, this book discusses one contender – sipXecs by SIPfoundry. You can look over their web site to get some idea of what sipXecs is, but in one respect it’s along the same lines as FreePBX, in that it provides a web-based GUI that allows you to do all the work of configuring your phone system from any web browser. The book is called Building Enterprise Ready Telephony Systems with sipXecs 4.0 by Michael W. Picher.
I’ve never personally so much as laid eyes upon a working sipXecs installation, so this isn’t going to be a review of sipXecs per se. But I suppose some are wondering what the difference is between sipXecs and FreePBX. The impression I got from reading this book is that the two have some differences in features, and even where there is feature overlap, there are differences in the way those features are implemented. If you are just counting features, FreePBX probably offers more, and many of those features have more configuration options. FreePBX would probably work very well in a home or small office. sipXecs, on the other hand, seems to have been designed by folks with experience in networking and larger business installations. If you were trying to link several branches of a medium-sized to large corporation together, and it’s crucial to have 100% uptime (or as close to that figure as possible), sipXecs might be a better choice (at least until someone high in the corporate food chain demands a feature it doesn’t offer). And if you’re a networking professional, you might find sipXecs more appealing. This is definitely NOT to say that sipXecs could not be used in a home or small office setting, nor that FreePBX could not be used in a large corporation for that matter, just that each may fill a particular niche better than the other.
So I will concentrate on the book itself, and I’ll let the publisher have the first word. Here is how they describe this book:
A clear and concise approach to building a communications system for any organization with the open source sipX Enterprise Communications Server
In Detail
Open source telephony systems are making big waves in the communications industry. Moving your organization from a lab environment to production system can seem like a daunting and inherently risky proposition. Building Enterprise Ready Telephony Systems with sipXecs delivers proven techniques for deploying reliable and robust communications systems.
Building Enterprise Ready Telephony Systems with sipXecs provides a guiding hand in planning, building and migrating a corporate communications system to the open source sipXecs SIP PBX platform. Following this step-by-step guide makes normally complex tasks, such as migrating your existing communication system to VOIP and deploying phones, easy. Imagine how good you’ll feel when you have a complete, enterprise ready telephony system at work in your business.
Planning a communications system for any size of network can seem an overwhelmingly complicated task. Deploying a robust and reliable communications system may seem even harder. This book will start by helping you understand the nuts and bolts of a Voice over IP Telephony system. The base knowledge gained is then built upon with system design and product selection. Soon you will be able to implement, utilize and maintain a communications system with sipXecs. Many screen-shots and diagrams help to illustrate and make simple what can otherwise be a complex undertaking. It’s easy to build an enterprise ready telephony system when you follow this helpful, straightforward guide.
What you will learn from this book
• Understand the complexities of an IP Telephony and Voice over IP network
• Build a clear process for migrating existing phone systems to an IP based system
• Deliver a solid foundation for any IP based phone system
• Quickly and easily get a sipXecs open source PBX running
• Deploy phones quickly and easily.
• Utilize Internet Telephony Service Providers to reduce monthly telephony bills
• Develop training materials to help successfully teach your users how to use the system
• Leverage sipXecs Automatic Call Distribution Queues to handle basic Call Center needs
• Operate and Maintain a reliable communications platform
Approach
This book was written to be a step by step approach to building a communications system for any organization. Care was taken to clearly illustrate with diagrams and screen shots all of the steps and concepts along the way. [Emphasis added – I’ll have more to say on that point!]
Who this book is written for
This book is written for network engineers who have been asked to deploy and maintain communications systems for their organizations.
Now, when I review a book, the thing I am looking at is whether the author accomplishes what he or she set out to do. In this case, the intent of the book is to instruct someone in how to set up a working sipXecs PBX. So, I look at whether the author seems to have a good grasp of his subject matter, and whether he can communicate his knowledge to the reader in a clear and understandable manner. A third consideration is whether the book is a good value for the money. Technical books often aren’t inexpensive, so I tend to mark them down if I perceive that there’s a lot of “filler” material in the book.
It’s difficult for me to decide how to rate this book. Does the author understand his subject matter? Yes, it certainly appears that he does. Does he effectively communicate it? Yes, the book was an easy read — I really didn’t feel like I was in “over my head” at any point in the book. Could you set up a working sipXecs phone system after reading this book? I think I could, but I can’t speak for anyone else. In fact, in many ways, this was one of the clearest and most understandable technical books I’ve read.
You sense a “but” coming, don’t you?
Well, there is, and it’s a big one. Did you notice above where the publisher said that “Care was taken to clearly illustrate with diagrams and screen shots all of the steps and concepts along the way”? Well, the book definitely contains screenshots — a LOT of screenshots. And normally, that would be very good thing, because as the saying goes, a picture is worth a thousand words. A screenshot would not add value to a book only in the case where it was useless “filler” material, and it’s pretty apparent that none of the screenshots in this book were intended to just be “filler.”
But, for a screenshot to be useful and not “filler”, it has to be readable. And in that regard, this book has a serious problem. If you buy the hardcopy edition of the book, I’d strongly urge you to also buy a good magnifying glass, because you’re going to need it to get anything out of those screenshots, unless perhaps you have perfect vision. Apparently the author (or whoever took the screenshots) has a widescreen monitor, and was running their web browser in full screen (or at least full width) mode. As a result, most of the text in the screenshots borders on microscopic, and some of the smaller print is unreadable (by me, anyway). When you take those extra-wide screenshots and reduce them to about five inches in width on a printed page, you need very good eyes (or good glasses) to make out the text. After trying to decipher the details in those screenshots for a while, I started to get a headache!
At first I thought maybe it was my eyes going bad — I am getting older, after all — but then I opened up some of the other books I have in my collection, including other Packt Publishing books, and none of them suffer from this problem. Frankly, if I were the publisher I’d stop the presses on this book immediately, and not let another copy go out the door until all the screenshots were re-done, but then that’s just me.
Now, that said, the book is not totally without value. I think that perhaps the author just might have realized he had a problem, because in many cases he repeats in the text most of what’s in the screenshot (at least the portion to which he’s calling your attention), so not being able to actually read the screenshot isn’t always such a loss — but unfortunately, it also relegates the screenshots more toward the category of “filler.”
So, would I recommend this book? Yes, for two classes of readers in particular:
Those thinking about setting up an Asterisk/FreePBX system that would like to know about available alternatives. It may be that the particular combination of features that you deem essential can only be found in one of either sipXecs or FreePBX, and by reading this book and the aforementioned FreePBX book, you’d have a pretty good idea of the differences in capabilities between the two.
Those thinking of installing a VoIP PBX in a larger organization, where reliability and scalability are far more important than the actual feature set. My impression from the book is that sipXecs is designed with larger businesses and higher call volumes in mind. That’s no reason that someone with a small business should shy away from it, but if you are very concerned about reliability and high “uptime” then you probably should at least give sipXecs some consideration. And if your organization is large enough to have people with degrees in computer networking in your employ, they might prefer working with sipXecs. This is not to say you can’t do a large installation using Asterisk, but now you have another choice, and this book can help you decide which is best in your particular situation.
If it weren’t for the screenshot issue, I’d be giving this book very high marks. The focus of the book is deployment in a business setting, and the author takes you through the steps for planning and implementing the system, whether you are replacing an existing PBX or starting from scratch. Having some knowledge of computer networking would be helpful, but as I noted, I’m no networking expert and yet I didn’t feel totally lost. In fact, if you know telephone systems but don’t know all that much about networking, you’ll find that just about everything you really need to know is explained, but without going into extraneous detail. You get the information you need to get the job done, but if you want to become a networking guru, you’ll need some other book for that.
I’m just really sorry that the bad screenshots marred an otherwise fine book, but I have to call ’em as I see ’em, and in my opinion they really are that bad. Whether that would matter to you is something only you can decide. I should mention that I was provided a hardcopy edition of the book for review, but Packt also offers an e-book edition in Adobe PDF format on their web site, and if you are comfortable reading e-books, I’d definitely go that route with this book, because most PDF readers will let you magnify sections of a page. So, the nearly unreadable screenshots might actually be very readable in the e-book edition. Also, if you do go the e-book route, be sure to scroll down the page and look for the offer, “Buy this eBook with FreePBX 2.5 Powerful Telephony Solutions eBook and get 50% discount on both. Just enter sip40xecs in the ‘Promotion Code’.” Seems like a good deal, especially if you’re wanting to compare FreePBX and sipXecs.
This is an edited version of a post that originally appeared on a blog called The Michigan Telephone Blog, which was written by a friend before he decided to stop blogging. It is reposted with his permission. Comments dated before the year 2013 were originally posted to his blog. In order to comply with Federal Trade Commission regulations, I am disclosing that he received a free product sample of the item under review prior to writing the review, and that any links to Amazon.com in this article are affiliate links, and if you make a purchase through one of those links I will receive a small commission on the sale.
This article was originally published in September, 2009.
Cover of FreePBX 2.5 Powerful Telephony Solutions
FreePBX 2.5 Powerful Telephony Solutions by Alex Robar (Packt Publishing) explains how to set up, configure, and maintain a powerful VoIP PBX using FreePBX. For those not familiar with FreePBX, it’s a “front end” for the Asterisk PBX software. Asterisk can be thought of as the “engine” that runs the PBX, but FreePBX is the user interface. It basically saves you the effort of writing Asterisk configuration files and dial plans by hand. Instead, you enter all the requisite information in FreePBX’s web-based GUI, and then when you apply the configuration changes (by clicking an orange bar at the top of the screen), FreePBX (re)writes the Asterisk dial plan and configuration files on the fly. This means that making significant changes to the call flow within the PBX, or adding new extensions or trunks, can be accomplished in a matter of seconds or minutes. It also means that you can have a fully functional PBX up and running in a few hours (perhaps even less than an hour if you’re exceptionally quick and it’s not your first installation).
As I like to do in reviews, before I begin I’ll give you a thumbnail description of what’s in each chapter (condensed from information on the Packt Publishing web site):
Chapter 1: Installing FreePBX – Installing FreePBX on CentOS 5.2 or Ubuntu Server 8.10
Chapter 2: Module Maintenance – how to install and update modules
Chapter 3: Devices and Extensions – explains the difference between Extensions mode and DeviceAndUser mode, and explains how to set up extensions and users. Also explains the different types of endpoints, and how to set up voicemail for a user or extension
Chapter 4: Trunks – discusses trunk types, setting up a new trunk, and checking trunk status
Chapter 5: Basic Call Targets – explains various ways to terminate calls on a FreePBX system, including Extension and Voicemail, Ring Groups, Conferences, Day Night Mode, and Phonebook Directory
Chapter 6: Advanced Call Targets – discusses Queues, Time conditions, and the setup of an IVR (Digital Receptionist)
Chapter 7: Call Routing – discusses Inbound routing, Follow Me and the VmX Locater, and Outbound routing and Least Cost Routing
Chapter 8: Recording Calls – focuses on everything you need to know about recording calls that pass through a FreePBX system
Chapter 9: Personalizing Your PBX – discusses Custom Music on Hold, Custom voice prompts, Directory search options, Customizing feature codes, Callback, Direct Inward System Access (DISA), CallerID Lookup Sources, PIN Sets, Misc applications, and Misc Destinations
Chapter 10: System Protection, Backup and Restoration – how to protect your system against failure, discussing both hardware methods (a good UPS and redundancy) and backups and restoration
Chapter 11: Security and Access Control – explains how to upgrade your operating system and Asterisk, plus various ways to secure your system against attacks
There are also four appendices:
Appendix A: FreePBX Modules
Appendix B: Feature Codes
Appendix C: Voicemail.conf Options
Appendix D: Common Trunk Configurations
I’m coming from a slightly different place in my review of this book than with other books I’ve reviewed. In this case I’ve already very familiar with the subject material, having helped set up and configure a FreePBX system that belongs to another member of my family. I was a bit afraid that because I’m already so familiar with the subject, I’d find several glaring errors or oversights. Happily, that proved not to be the case – this book is a good, solid treatment of setting up and configuring a FreePBX system. In fact, the title should have been “How to set up and maintain a FreePBX system”, because that’s exactly what this book explains.
The first thing that impressed me about this book is that there was no “filler” material. Very often, with technical books, the author really only has about 75 to 100 pages of actual material, but because publishers like to publish books that have somewhere around a couple hundred pages, the author will flesh out the book with a history of the software, a profile of the developers, comparisons with competing products, and (if they are really desperate for material) a history of the Internet. 🙂 That is not the case here. After a very short preface, the author jumps right into the subject material, starting with how to install FreePBX and then continuing through subsequent chapters with virtually everything you need to know about configuration. While not every chapter may be meaningful to every reader (personally, I’ve never had the need to record a call — so far — but it’s nice to know that FreePBX can do it), the book at least touches on all the major features of FreePBX.
If I had to make one criticism of the book, it’s that in some places it reads a little bit too much like an instruction manual. And that’s not necessarily a bad thing, because FreePBX has badly needed a good manual to assist first time users in getting it set up and running. This is the manual that should have come with FreePBX. That said, the author really doesn’t touch some of the problems frequently encountered by new users. For example, in the discussion of SIP endpoints, he notes that “SIP can be problematic when traversing firewalls and other NAT devices” and that “Configuration can be particularly troublesome if both the endpoint and the FreePBX system are behind their own firewalls” (p. 44). And there he leaves the reader hanging. There is no discussion of how to overcome the problem, nor is there a pointer to the FreePBX FAQ’s or How-To’s anywhere in the book. While many readers may not encounter this issue, a fair number will, and it would have been nice if they’d been thrown a bone, if only in the form of a pointer to the FreePBX page that addresses the issue.
In my opinion, perhaps the biggest omission is in the discussion of Trunk setup in Chapter 4. This was really the only chapter in which I got the distinct feeling that the author may have been in just a bit over his head, and perhaps did not fully grasp the subject matter covered in the chapter. Not only are there errors in his examples of dial pattern usage (p. 81 – under no circumstances would you use two pipe characters in the same dial pattern, as is shown for some of the toll-free number examples), but when discussing IAX2 and SIP trunks (p. 83), only cursory information is given about how to populate the PEER details and USER details fields. Nor is it explained that with many commercial VoIP providers, the USER context and USER details fields are not used, and should be left blank. However, in the author’s defense, I suspect that I understand why this may have happened — there probably aren’t ten people on the face of the earth that can give you a full explanation of all the options that could possibly be used in the trunk PEER and USER details fields, and when and how each option should be used. Trunk configuration is probably the most difficult part of setting up FreePBX, precisely because there’s no definitive guide on how to do it correctly. In most cases, I suspect that finding the correct options to use with any particular provider is a matter of trial and error — you make educated guesses about which options might be needed and how they should be configured, and if you find a combination that works, perhaps you post it so that others can use it. Some of the known working trunk configuration settings appear in Appendix D of the book, but there are more sample configurations available at the FreePBX web site.
I only mention this because I was hopeful that maybe someone would finally provide a really good how-to on setting up FreePBX trunks, since this is something that almost always confounds new users, and even causes experienced users to get a few (more) gray hairs on occasion. Had I been writing such a book, and had I really understood the subject, I might have given several pages to the subject of trunk configuration in general, and PEER and USER details in particular, not just a few cursory paragraphs. On the other hand, most users will probably seek out a tested and working trunk configuration for whatever provider(s) they use. It’s not as though there isn’t any online help on the subject, but — and this is another minor criticism — for some reason the book barely mentions the availability of online help (for example, unless I missed it there is no specific mention of the FreePBX How-Tos that address several of the issues encountered by new users). This is why I say that at times the book reads like an instruction manual — it gives you all the basics, but seldom touches the “edge cases”, the little quirks and problems that may be encountered by a significant subset of users, but not by all.
However, I don’t want to leave you with the idea that this book is simply a rehash of information that could be found online — even if that were the case, it presents that information in a logical manner that is easily understandable by the reader. But, many essential functions of maintaining a FreePBX system happen outside of the FreePBX interface. For example, you cannot update your operating system or Asterisk from within the FreePBX GUI, but the book explains how to do both. Chapters 10 and 11 (on System Protection, Backup and Restoration, and Security and Access Control) deal with functions that are at least partially handled outside of FreePBX. In some instances the author provides useful shell scripts that automate particular tasks (for example, deleting old, outdated backups to avoid filling up the hard drive). And in many cases, the book does explain things that new users need to know, but might not know that they need to know — for example, the explanation of Codecs and the penalty involved (both in terms of system performance and call latency) in transcoding between codecs.
Anyway, the bottom line is this: Let’s say your boss wants you to set up a new office phone system using Asterisk, and gives you a couple of weeks to do it. If you have no prior experience with Asterisk, you will almost certainly want to use FreePBX (the alternative is writing dial plans and configuration files by hand, and trust me, you don’t want to do that unless you are the sort of person who enjoys writing source code for major projects, and even then you probably don’t want to do it if you’re under any sort of time deadline). And if you’re going to use FreePBX, and you don’t want to spend hours and even days ferreting out information on the Internet, you need this book. Get your boss to buy it (there’s even an e-book version if you need it right now), then just follow the instructions, chapter by chapter. In a few days time, you’ll be well on your way to becoming a FreePBX expert. That’s partly because FreePBX is so easy to use in the first place, but also because the book tells you pretty much everything you need to know, in a very understandable manner. If you get stuck, help is available at the FreePBX web site and at other various locations on the Internet.
If you are a long-time FreePBX user, you may find that you already know much of what’s in this book, but then again it might surprise you how much can still be learned. For example, I found several good suggestions for adding additional security to a FreePBX system in Chapter 11 of the book — and let’s face it, many of us are probably a bit lax about securing our systems to the greatest possible extent (and that could be a very costly mistake).
One other point I should make — as the title of the book implies, it deals with a particular version of FreePBX, namely version 2.5. Of course, as so often happens with a book about software, the ink is barely dry on the paper when a new version comes out. FreePBX 2.6 has already been offered as a release candidate, and beta versions of FreePBX 3.0 are being made available. From a user’s standpoint, version 2.6 will be nearly identical to 2.5 – there may be a few added options and such, but for the most part they are not things that you would need to worry about, or that would detract from the accuracy of this book. However, FreePBX 3.0 will be a major rewrite, but it’s only available in an early beta version, and unless you are an experimenter that wants to be on the bleeding edge, you don’t want it yet. Whenever you do move to FreePBX version 3.0 — and I’d be very surprised if a full release version is much closer than a year away — much of what you’ve learned about FreePBX 2.5 and subsequent versions will still be applicable (and also, I suspect that people will be using FreePBX 2.x versions for quite some time to come).
This is an edited version of a post that originally appeared on a blog called The Michigan Telephone Blog, which was written by a friend before he decided to stop blogging. It is reposted with his permission. Comments dated before the year 2013 were originally posted to his blog. In order to comply with Federal Trade Commission regulations, I am disclosing that he received a free product sample of the item under review prior to writing the review, and that any links to Amazon.com in this article are affiliate links, and if you make a purchase through one of those links I will receive a small commission on the sale.
Cover of OpenVPN: Building and Integrating Virtual Private Networks
Before I start, let me give you a brief description of what’s in each chapter (this is taken directly from the Packt Publishing web site):
Chapter 1 looks at what VPNs are, how they evolved during the last decade, why it is necessary to modern enterprises, how typical VPNs work. The chapter also covers some essential networking concepts.
Chapter 2 explains VPN security issues, including symmetric and asymmetric encryption, the SSL/TLS library, and SSL certificates.
Chapter 3 introduces OpenVPN. In this chapter, we learn about the history of OpenVPN, how OpenVPN works, and how OpenVPN compares to IPSec VPN applications.
Chapter 4 covers installing OpenVPN on both Windows, the Mac, Linux, and FreeBSD. It covers the installation on Linux from the source code and RPM packages. Installation on Suse and Debian is covered in detail.
In Chapter 5, an encryption key for OpenVPN is created and it is then used to setup up our first OpenVPN Tunnel between two windows systems in the same network. The key is then copied on a Linux system and this system is connected through a tunnel to the first windows machine.
Chapter 6 shows how to create x509 server and client certificates for use with OpenVPN. easy-rsa which comes with OpenVPN and is available for both Windows and Linux is used.
Chapter 7 reviews the syntax of the command line tool openvpn, which enables building tunnels quickly. The configuration options of openvpn are covered in detail with examples.
Chapter 8 shows how to make the example tunnels created earlier safer and persistent by choosing a reliable combination of configuration file parameters. It then covers how to configure firewalls on Linux and Windows to work with OpenVPN.
Chapter 9 focuses on using xca, the advanced Windows tool with which x509 certificates can be easily managed. Its Linux equivalent, Tinyca2, which can even manage multiple certificate authorities, is also covered.
Chapter 10 covers advanced OpenVPN configurations, including Tunneling through a proxy server, pushing routing commands to clients, pushing and setting the default route through a tunnel, Distributed compilation through VPN tunnels with distcc, and OpenVPN scripting.
Chapter 11 shows how to debug and monitor VPN tunnels. It covers standard networking tools that can be used for scanning and testing the connectivity of a VPN server.
Although this may seem like a strange subject for this blog, I have recently become interested in the concept of Virtual Private Networks (VPN) because of the increasing number of attacks on Asterisk-based system based on spoof SIP credentials. SIP, the most popular protocol for VoIP, is an inherently insecure protocol – it relies on password protection only, and on most Asterisk boxes and in many VoIP devices and software products, the password is stored in plain text. On many systems, the user name is the same as the extension number, so all a potential intruder has to do is start a brute-force attack guessing passwords. The use of strong passwords along with the use of software like Fail2Ban (with iptables) can help minimize the exposure, but in the end it’s still only password protection.
Therefore, my feeling is that it would be much better to restrict extensions to access from within the local network (wherever possible), using the permit/deny fields in FreePBX or some similar mechanism, and then “tunnel” remote extensions through a secure VPN, so they appear to be on the local network. The VPN could do the heavy lifting for security (even making the actual calls secure, although that wasn’t a priority in my situation). My problem was that I knew next to nothing about VPN’s, and most of the pages on the Web seemed to assume at least some prior knowledge. I needed something that would take me from zero knowledge to VPN guru. Unfortunately, at my age it’s a case of “the spirit is willing but the brain is a bit weak”, so I realized that the “guru” part might not come very quickly (just as a comparison, I’ve been playing with FreePBX since back in the Asterisk@Home days, and there’s still a lot I don’t understand, but for the first year or so I felt totally lost).
Since the folks at Packt Publishing were willing to send me a review copy of OpenVPN: Building and Integrating Virtual Private Networks, I decided to see if I could actually learn anything from the book. The first thing you need to know is that there are many types of VPN’s out there, and each will only communicate with its own kind, as it were. The problem with most other tunnels is that they are either not all that secure, or contain proprietary code, or are incredibly complicated to set up and use (or some combination of the above). OpenVPN has several advantages, perhaps the biggest being that it’s open source (so you can, if you are so inclined, examine the code and make sure there are no “backdoors” built in), that it can be as secure as you want it to be (and it’s not that difficult to make it very secure), and that it doesn’t rely on a third-party service over which you have no control (like one VPN application that touts itself as “zero-configuration”). So of all the VPN methods out there, OpenVPN seemed like a logical choice.
Now, having said that, the book covers its subject in a very logical manner. Advanced readers (those already familiar with the principles behind VPNs) might find the introductory material in the first chapters a bit tedious, but believe me, it was just what I needed to help me get a grasp on the subject. As you go further through the book, there are many actual examples, first showing how to set up a working VPN tunnel, then how to add additional security, and finally how to troubleshoot connections. If you are brand new at this, like me, you will probably find that you learn a great deal from the first chapters but find the latter chapters (especially Chapter 10) a bit beyond your comprehension at first. However, the person who has some networking or VPN experience under their belt may think the first chapters a bit elementary, but will find the real meat they are looking for in the latter parts of the book. Either way, I guarantee you will come away with a greater comprehension of the subject.
The book shows how to install OpenVPN on several platforms (Windows, Mac OS X using Tunnelblick, FreeBSD, and SuSE, Debian, and Redhat/Fedora based versions of Linux), but it seems like some platforms are better covered than others. A disproportionate number of examples and screenshots seem to be based on a Windows installation, whereas the Mac gets very little coverage. Because there are so many variations of Linux, the coverage there is mixed, although it seems like SuSE and Debian are better covered than Fedora-based versions, which was just a little bit disappointing because most Asterisk and FreePBX systems are based on CentOS, which is a Fedora-based OS. But most of the information in this book is not OS specific, so I didn’t have any real problem following along.
The biggest disappointment for me was in Chapter 8, where the book covers the use of Webmin, but primarily as an aid to administration of the Shorewall firewall. Many Asterisk/FreePBX systems don’t use Shorewall, but instead use iptables (if they have a firewall on the Asterisk server at all). But what was really disappointing was that there was no mention of, nor instructions for the use of the OpenVPN + CA module for Webmin (page is in Italian, but here is a description in English). I can only guess that because the book was first released in May, 2006 and version 1.0 of the Webmin module had only just been released in January of that same year, the author perhaps hadn’t had an opportunity to work with the module before the final draft of the book was submitted to the publisher. I hope that if this book is ever updated and republished, there will be consideration given to adding a chapter on the use of the Webmin module to set up and administer OpenVPN. In the meantime, you can find instructions for using the OpenVPN + CA module in The ‘Point and Click’ Home VPN HowTo Guide.
That said, I felt I learned a great deal from this book. I was able to set up an OpenVPN server (using the Webmin module, but the book definitely helped me understand the purpose of the various options, and when I checked the configuration file that the module generated I was able to spot a couple of things that weren’t the way they should be for my setup and was able to change them) and the Windows client. It all worked beautifully.
My project now, when I have absolutely nothing else to do, is trying to get the OpenVPN client running on an Asus WL-520gu router that has the DD-WRT firmware installed (I inherited this project from someone else who couldn’t do it). So far this has proven to be a tough nut to crack – although it should be easy because (if you get the right version of DD-WRT) there is a built-in OpenVPN client with a handy configuration page, it just doesn’t seem to work “out of the box” – and from what I’m reading on the ‘net, for every one person who says they’ve got it working, there are about twenty others who have become incredibly frustrated by the process (example here – note that the original poster says he got it working, but that’s followed by about 16 pages of comments, mostly by people who just can’t seem to get it to go). It’s a bit strange because the Windows client will work perfectly (indicating it’s not an issue with the server) but the firmware client in DD-WRT just doesn’t seem to work. If I ever get it figured out, I’ll try to post what I did in this blog, but so far I’ve had no luck. That, however, is not the fault of the book – in my opinion it’s the fault of the writers of the DD-WRT firmware, who apparently included a half-baked OpenVPN client interface in the firmware (I know, it’s free software so I can’t really complain, but one does wish that they’d taken a bit more care to make sure it worked).
After having read the book, I do feel fairly confident that if I should throw in the towel and decide to dump DD-WRT and install a different firmware on the router (I’m thinking about trying the Tomato firmware with USB support) I would be able to install an OpenVPN client from scratch and make it work. Probably the main reason I haven’t wanted to do that is because I very much prefer using a GUI to do things, and would like to try to make the OpenVPN GUI in DD-WRT work (even if it requires a little help), but so far that doesn’t seem to be panning out.
But I digress a bit – anyway, if you are wanting to learn about OpenVPN, whether or not you are a rank beginner you will benefit from this book. The numerous examples and screenshots make it almost impossible to fail to get an OpenVPN tunnel up and running (providing you’re not using a questionable firmware client). And, as I said above, the book is laid out in a very logical progression, so I really didn’t feel totally lost at any point (as so often happens when I try to read technical books). Especially in the case where your boss suddenly decides he needs VPN tunneling capability, and wants you to have one up and running in a very short timeframe, this would be the book to get!
I recently had the experience of trying to help someone make a 
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