Mini-review of Sangoma U100 USBfxo device


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.

EDIT: For more comments/opinions on this device (and on this review), see this thread on the PBX in a Flash forum.

8 thoughts on “Mini-review of Sangoma U100 USBfxo device

  1. I have 14 of these devices working with no issues is 7 locations.- seems to me thaat you might be the dog; not the Sangoma device! Yes, I did have one issue with the setup, but a quick response from Sangoma sorted me out.

    Are you sure you don’t have a bone to pick with Sangoma? (i.e chip on your shoulder) , the way you solicit a manufacturer to slide you a device to test seems a little under-handed to me.


    1. Well, let me put it this way – I don’t get paid a dime for writing this blog, and if once in a very great while I can get a manufacturer to slide me a free product with the understanding that I’m going to give them an HONEST review (and also disclose that I got free product), that doesn’t violate my sense of integrity. If you think it’s underhanded, then feel free to read someone else’s blog, but I’m certainly not going to let you define my sense of morality! Personally, my feeling is that if a blogger’s not getting paid to write, I have no problem with them getting a free product or book every now and then (and don’t kid yourself that I’m the only blogger that feels that way — there are guys out there that will accept product with the idea that they will only write a glowing review, but I have never operated that way and never will).

      In this case, although I did in fact request a sample from the manufacturer a few months ago, I really didn’t expect to get one (large manufacturers with an established reputations often only want reviews from big-name publishers), and I can honestly say that this would not have caused me to write a bad review. The only difference it might have made is that if the manufacturer had provided me a review sample, I would have felt obligated to publish a review of some kind, and say what I honestly felt about the unit. However, if a manufacturer does not provide a review sample, then I don’t feel any obligation to write about it — in that case. I might write a review only if I felt that I had something significant (good or bad) to say about the unit.

      I think the big thing that motivated me to write this article was that given Sangoma’s reputation, and the fact that the unit was obviously not functioning as expected, I was rather taken aback that they seemed less than eager to swap out the unit for a replacement. This suggested to me that perhaps the device has a hardware flaw that they know about and have not yet been able to correct, so they knew that shipping another unit wouldn’t accomplish a thing. The fact that they had me turn off hardware echo cancellation (and that the original problem disappeared when I did that) suggests to me that’s where the problem lies. I do understand, and as much as said, that others may not experience this problem — it may have been that the particular unit had a defect, or it may have been something unique to our particular local environment. Since we were never offered a replacement, I have no way of knowing.

      If I had to guess — and this is solely intuitive — it would not surprise me if things like the length of the loop (C.O. to unit), condition and type of line (copper, or mix of copper and fiber back to the C.O.), and even the line impedance might make a difference. But Sangoma’s tech support never even asked about things like that, so I’m guessing they thought (up to that point, anyway) that their device could handle all situations. Well, the one we had couldn’t. So if I had a “bone to pick”, it was with their apparent unwillingness to swap out the unit, so that we could better determine the source of the problem. I also didn’t like the fact that it was advertised as being an “easy installation”, which in my opinion is definitely not the case for a first-time user (though after you’ve done it as many times as you have, you can probably do it in your sleep). And even if they had provided me a review unit, and it had worked as expected, I would definitely still have mentioned that the installation was far from “plug-and-play!”

    2. One other point – when you post a comment, I get to see the IP address you posted from (Cogeco Cable is your ISP). Since you apparently like to call into question question the ethics of others, I have a question for you – would you disclose if you were an employee of, or otherwise affiliated with Sangoma? I just find it curious that they’re in Canada, and you’re writing from Canada, and while Canada is a huge country, you’re apparently somewhere in Ontario, which just makes me wonder if maybe you’re connected with the company in some way and didn’t like it that someone gave you a less-than-glowing review. Frankly, I just don’t like your implication that I’d give someone a bad review just because I had requested a review sample (and how would you know that, anyway?) and they didn’t provide one. That’s not how I operate. But if you are going to criticize someone over a review, maybe you should disclose whether you have some affiliation with the manufacturer in question.

  2. In case it matters to someone else, I too have been battling (and posting elsewhere) about these *exact* problems/experiences with the U100 – and I mean precisely the same issues.

    My first Sangoma purchase due to the reputation I have heard about on their card products, and I have to agree as nice/helpful as the tech has been I worked with the net result is that the product itself just does not work. The sales pitch lured me in, the reality is pushing me away possibly permanently from Sangoma. Six weeks into tinkering, I have given up & will chuck the unit in lieu of a better product elsewhere.

  3. The echo cancellation clipping could be solved with a firmware update or never if the processor is not powerfull enough for the task…

    is the USBfxo working today?

  4. Just as a data point for anyone reading these comments, here’s another thread where someone is having difficulty with these devices (this is the start of the thread; you can click the links at the bottom to follow the reply chain):

    The reason I point this out is because they are trying to use two of these devices with an Acer Aspire Revo, which is one of the typical uses I had in mind when I first wanted to review one of these units. Since the Revo (along with several other low-power computers that will run Asterisk) does not have card slots that will accept hardware FXO cards, an external unit with a FXO port is the only option. As of today (January 3, 2011) the person who started the thread apparently has not been able to resolve the issue ( is the last message shown in the thread as I post this).

  5. We have done most R & D but still facing caller ID issue in india. We got the caller id two times only within week. what should be the issue?

  6. NOTICE: All comments above this one were imported from the original Michigan Telephone Blog and may or may not be relevant to the edited article above.

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