Month: January 2012

I no longer recommend using Asterisk’s Google Voice support — try these methods instead!

 

Important
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.

EDIT (May, 2018): FreePBX and Asterisk users that wish to continue using Google Voice after Google drops XMPP support should go here: How to use Google Voice with FreePBX and Asterisk without using XMPP or buying new hardware.

This article was originally written in January of 2012, and has been heavily edited in an attempt to update it a bit.

Not that anyone probably cares what I think, but anyone who regularly reads this blog (or any of the other VoIP-related blog that cover Asterisk) may have noticed that prior to the release of Asterisk 11, Asterisk’s support for Google Voice had become less and less reliable over time, particularly for incoming calls. You have to do all sorts of “tricks” to make it work, and these usually involve adding delays that don’t always fix the problem, inconvenience your callers, and possibly cause more hangups as people get tired of waiting for you to answer the phone.

Therefore, I suggest that if you are using a version of Asterisk earlier than Asterisk 11, you stop using Asterisk’s Google Voice support completely. Assuming that you feel you must keep using an older version of Asterisk, I suggest trying one or more of the following:

  1. Use YATE as a gateway between Asterisk and Google Voice. See Using YATE to overcome Google Voice issues in FreeSWITCH and Asterisk, this article and this forum thread on YATE in a Flash, and this thread on YATE Tips & Tricks). YATE is what powers Bill Simon’s gateway (mentioned below). See comments by Bill and pianoquintet under this article.
  2. Use Bill Simon’s Google Voice-SIP gateway to handle your Google Voice calls. Some people may not want to rely on an external service for this, while others may very much appreciate having the option. I mention it for those in the latter group. For more information see Bill Simon’s Free SIP-to-XMPP Gateway Easily Puts Google Voice on Your VoIP Phone (Voxilla). While the linked articles talk about using the gateway with a SIP device, it can be used as an Asterisk trunk.  EDIT: As of April 7, 2015 the Google Voice Gateway has been relaunched and there is now a one-time fee to sign up.
  3. If your only issue is with incoming calls, you could use a DID to bring the calls into your system.  But keep in mind that Google Voice does not like it when calls are answered the moment they connect, so in your FreePBX Inbound Route be sure to set the “Pause Before Answer” option to at least 1.  I have found that a 1 second pause is sufficient, but I’m not saying that is the correct value for everyone, or even that everyone will need to include such a pause (some DID providers may delay the call sufficiently before connecting through to your system that the pause isn’t needed).

At this point, any of those would likely produce better results than using the Google Voice support in any version of Asterisk prior to Asterisk 11.

EVERYTHING in this article is my personal opinion.  Nothing here should be taken as a statement of fact.

EDIT:  Ward Mundy reports that he just may have found a workaround for the incoming calls issue — see this thread in the PBX in a Flash forum.

Why do Western Digital hard drive power supplies leak so much AC voltage?

 

Important
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.

We recently changed out a case on a computer power supply.  The new case is metal whereas the old one was plastic, and as I was plugging in a USB cable from a USB hub I got a shock.  Not only that, when I accidentally touched it to the bottom of the computer’s case, the computer power supply completely shut down and would not restart until I physically removed the power cord and plugged it back in.  Since this hub had worked just fine with the old case, it led me to wonder what the issue was.  I put a voltmeter on the shell of the USB cable and measured about 50 volts AC to ground!

To make a long story short, I have four external USB drives plugged into that hub and they are all Western Digital. Every single external hard drive had AC voltage on its USB cable shell (when disconnected from the hub), whereas no other devices had more than a volt or two.

That led me to disconnect the power supplies from each of the hard drives, at which point I made a, um, shocking discovery!

I measured the voltage from the power supply DC plugs to ground.  For this test I plugged them into an outlet on a totally different circuit from the one I plug my computers into, since a friend has suggested that the outlets might be miswired (hot and neutral reversed).  I tested for that possibility and that was not the case, but it was still easier to take them out to the kitchen for this test.  I photographed the results for three of them but a fourth gave similar results.  I’m sorry that the pictures are a bit blurry but if I’d used flash it would have washed out the LED display so the exposure times were a bit longer than I would have liked, given that my hand isn’t all that steady.

Western Digita Power Supply #1 - 44 volts leakage

Western Digita Power Supply #2 - 57 volts leakage

Western Digita Power Supply #3 - 44 volts leakage

EDIT: For a few hours after I first posted this, I had image duplicated as . Sorry about that.

A few observations I noted while testing the voltage:

It didn’t matter which way the AC plug was inserted into the socket – the voltage was the same or very nearly the same (within a couple of volts) either way.

It didn’t matter whether I measured to the center or the shell of the DC plug – the voltage was exactly the same either way (this makes me think the leakage might be through a capacitor or capacitors, since otherwise there would be a DC short).

Whatever voltage I measured at the power supply found its way to the USB plug shell once the power supply was connected to the hard drive.

I measured this on FOUR different power supplies, all ones that came with Western Digital hard drives of various sizes. On three I got the 44 volt reading and on one I got 57 volts.

If it were just one or two power supplies doing this, I’d suspect a flaw in that power supply. But since every single one of them is doing it, I have to think it is something inherent in the design of the switching power supplies used with external hard drives. For some reason this never caused any problem with my old computer or case but this new one (new case) can get really strange if you connect or disconnect the USB hub while it is running and the power cable is connected. I just hate the fact that there is this much stray AC but it must be a problem specific to the hard drive power supplies so I don’t think there is anything I can do about it.

I don’t know of any way to correct this problem, or even if it really is a problem. But I REALLY don’t like it!

By the way, I don’t mean to impugn Western Digital specifically, it’s just that right now all four of the external drives connected to this particular computer are WD’s.  I do NOT know whether or not this problem affects power supplies that come with other makes of hard drives (if anyone wants to test yours and post the results in a comment, I’d appreciate it, but please don’t unless you have worked with electricity enough to know how to do the test safely, since I will not be responsible if you fry yourself or your equipment because you didn’t know how to do the test!).

DynDNS (mostly) discontinues free DNS service

 

Important
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.

Dynamic DNS service selections in DD-WRTOver the years, many people have used DynDNS as a way to get a free domain name that will “track” their actual IP address, even if their ISP changes it.  Apparently that free ride has all but come to an end.  If you read the instructions that How-To Geek posted in their article How To Easily Access Your Home Network From Anywhere With DDNS, you will note that when you go to the DynDNS site now, it looks nothing like it did then, and the totally free option seems to have disappeared.

Apparently if you have an existing DynDNS account you can keep it as long as you don’t let it expire, but if you do let it expire or if you are trying to set up a new DynDNS account for yourself or someone else, the free option is no longer shown. It appears that now the only way to get a free DynDNS account is to sign up for a 14-day DynDNS Pro Free Trial and then cancel it before the free trial period is up. Then, “You may keep one hostname free of charge for trying the Pro Trial.” The problem with this is that you have to provide a major credit card to sign up for the trial. This will be a show stopper for many users (it definitely takes DynDNS off my list of recommended services).

I had recommended using DynDNS in my article, Using DynDNS to solve the problem of keeping a firewall open to remote users at changeable IP addresses. Now I sort of wish I had recommended someone else.

Some home routers support several Dynamic DNS services, and one of the most popular is No-IP. My guess is that they will be the main beneficiary of the decision by DynDNS to make their free service less accessible. I think they have been around nearly as long as DynDNS (if not longer) and I’ve not heard anything negative about them, so I now recommend you check out No-IP in preference to DynDNS, unless you enjoy having to give up your credit card information and then having to remember to cancel a “free trial” within an allotted timeframe.

To those router manufacturers that only offer DynDNS as a DDNS option, please consider adding No-IP (and maybe a few others) as a DDNS option in your next firmware upgrade.  Those that have replaced their router’s firmware with DD-WRT have the option to use DynDNS.org, freedns.afraid.org, ZoneEdit.com, No-IP.com, 3322.org, easyDNS.com, TZO.com, and DynSIP.org (or you can use another “custom” service). I do not know if all of those have a free service offering but I believe that most of them do. So, commercial router manufacturers could offer options other than DynDNS, and I hope they’ll consider doing so.

 

Related articles

Interesting thread on integrating Speech to Text with Asterisk and PBX in a Flash

 

Important
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.
An old microphone
Image via Wikipedia

I just wanted to call your attention to this thread on the PBX in a Flash forum:

Exploring Speech to Text

This thread explores the possibility of adding a simple speech to text demo, and also discusses the possibility of transcribing e-mails to text.  It uses Google’s speech recognition service, and it is free to use.  I doubt you would be free to use it in any commercial application, but for those that just like to tinker with new capabilities for your Asterisk server, you might find this interesting.

I haven’t personally tried it yet, but I will say that if you are using some FreePBX based distro other than PBX in a Flash, you may need to remove the calls to the Flite speech synthesizer (or install Flite support).  I hate Flite (I think the voice quality sucks harder than a black hole — okay, maybe I exaggerate a little, but Cepstral voice synthesis is much better than Flite — unfortunately Cepstral is not free) so I’m not going to tell you how to install it.  Flite’s only used in the demo in the first post so if you are trying to do something else (such as attempt voicemail transcription, as discussed in the thread) you probably don’t need it anyway.

What would be nice would be the ability to dial a code, record a short message, and then have a transcription e-mailed to the address you use for voicemail notifications.  THAT is something I’d actually use on occasion!

EDIT: After posting this, I tried a basic installation on a NON-PBX in a Flash system.  Besides removing the references to Flite, I found I had to do the following:

  1. Change ownership of /var/lib/asterisk/agi-bin/speech-recog.agi to  asterisk:asterisk
  2. Install the perl modules mentioned in the “use” statements in /var/lib/asterisk/agi-bin/speech-recog.agi
  3. Install flac (some users may also need to install sox, but I had installed that previously).