TUTORIAL Sangoma A200R, or how I almost lost my mind...

[boeingpilot]

Since getting started in the open source PBX movement, I've several times installed Sangoma analog boards, primarily the A200R. board. Never totally pleased with them (I personally find getting the software / firmware straightened out to be confusing, buts that me). That said, three recent issues had me totally pulling my hair out.

First (and second) issue are not totally Sangoma's fault, but I wanted to relay what happened so someone else doesn't waste hours on end chasing ghosts.

About two months ago I was recycling a used trixbox appliance for one of my customers. These boxes, while not power houses, came with the A200 boards, and the higher end units had dual power supplies and the requisite dual hard drives. PIAF installs with no problems, and with a little tweaking with either LCDproc or LCD4Linux, the nifty LCD display can show useful information. In any event, my customer was connecting to a Comcast 4 port Arris TM series voice modem. After we had the system up and running, we found that with more than two lines going at time, the Arris voice modem would go into an 'alarm' mode with all LED's flashing. Disconnecting the Sangoma card from the voice modem would result in the modem returning to normal.

Initially both Comcast and I thought it was a bad voice modem, and Comcast replaced it, but we still had the issue. This is where the troubleshooting dragged out. At first I thought the Sangoma card was bad, so pulled the Sangoma out and installed a tried and true clone TDM410P card. Still the same problem! Now it should be noted, we were still testing, so I had kept the Sangoma provided cables in place, even though they use RJ9 connectors on the adapter end and RJ11 connectors on the demarc end. These cables are provided by Sangoma, and are made of flat cable, not twisted pair (what I used to call silver/satin, even though these are yellow).

Both myself and the customer's IT consultant went around and around checking configurations on the PIAF box, and couldn't find a problem. After about two hours it dawned on me that the ONLY common configuration that remained were the cables. So, I made up jumpers using Cat 5 cable. All of a sudden, everything worked! I did send a note to Sangoma of this issue with their cables, recommending that they really should provide twisted pair cables if they persist in using connectors that are not readily available.

I filed that away in my head and about two weeks ago was installing another PIAF system. In this case, we were using a compact case Dell, so needed to use the low profile bracket with the Sangoma card to make everything fit. The first problem was that with the latest version of PIAF Green, the Sangoma software would not load. After comparing my working systems to non- working, I discovered that the latest Sangoma driver will not support the latest version of Asterisk 11. So, after rolling back the asterisk version, I finally got the drivers and software to load. (thanks Sangoma.... not)

After that, got to the customer site to find they too are using the Comcast Arris voice modem. Sure enough, using the Sangoma provided cables, same exact problem, two calls going and the box goes into alarm and the ports start shutting down. Fortunately, I'd just seen this, so made up new cables (I now have the right connectors and crimp tool) and the problem immediately went away.

Lessons learned

- Cable counts! Even on voice, twisted pair is preferable to flat, as we may be radiating interference. I'd also bet that weird artifact on an install could very well be due to using non-twisted cabling to analog ports. Sangoma, I'll say it again, ditch the cheap flat wires and give us an option for twisted pair!
- Use caution when connecting analog ports to non-traditional analog lines. The ironic thing is that I have the same setup at another customer working, but who knows if the internals of the Arris boxes have changed over time.
- Never assume that vendors are updating drivers. One would think with the amount of product that Sangoma sells they would keep their drivers current, but the newest driver was over 6 months old. What worked a month ago might not work this month if one component of the setup is updated and the other isn't.

Hopefully this will help others building systems.

Scott

 

[islandtech]

The only major issue that I've had (30+ years of telephony) using silver satin was crosstalk on 50+ feet feeding a 2 line analog phone. I've had a RS232 dumb terminal working on 180 feet on silver satin!
Majority of issues nowadays is T/R reversals, improperly wired jacks & plugs by TWC/Comcast/other installer types with no telephony experience.
How did Comcast terminate the analog lines, to jacks, a 66 block, or just say here are your numbers on these ports?
The TM604 ports are from left to right 1)line 1/2 2)line 2 3)line 3/4 4)line 4. The Sangoma ports are from the bottom up 1)port1 2)port2 3)port3 4)port4, but you probably knew that already.
I'm not sure of Sangoma's utilization of the other 2 conductors in the jack, but if using the Sangoma supplied (4 conductor) cable to connect the Sangoma port 1 to the Aris port 1, then line 1 and 2 from the Aris is on the Sangoma port. Who knows what happens when line 1 is in use and ringing voltage starts on line 2. I would use a 2 conductor cable between each device or terminate them with 4 jacks wired for only T/R (2 conductors). That's just my 1/2 cent!

 

[atsak]

Ya, the problem with Sangoma is that they are 100% reliable, but configuration can be a problem with newer DAHDI and Asterisk, and even kernel. Long story short I've stopped using in system boards and went to the Vega. Cost wise I believe they're the same (potentially cheaper in some cases) and give you better versatility if you lose your PBX anyway. I couple this with a backup of client systems on rentpbx or my own hyper V cluster and can pass the copper if needed (where copper is desired for the near 100% uptime) over the net.

 

[boeingpilot]

The only major issue that I've had (30+ years of telephony) using silver satin was crosstalk on 50+ feet feeding a 2 line analog phone. I've had a RS232 dumb terminal working on 180 feet on silver satin!
Majority of issues nowadays is T/R reversals, improperly wired jacks & plugs by TWC/Comcast/other installer types with no telephony experience.
How did Comcast terminate the analog lines, to jacks, a 66 block, or just say here are your numbers on these ports?
The TM604 ports are from left to right 1)line 1/2 2)line 2 3)line 3/4 4)line 4. The Sangoma ports are from the bottom up 1)port1 2)port2 3)port3 4)port4, but you probably knew that already.
I'm not sure of Sangoma's utilization of the other 2 conductors in the jack, but if using the Sangoma supplied (4 conductor) cable to connect the Sangoma port 1 to the Aris port 1, then line 1 and 2 from the Aris is on the Sangoma port. Who knows what happens when line 1 is in use and ringing voltage starts on line 2. I would use a 2 conductor cable between each device or terminate them with 4 jacks wired for only T/R (2 conductors). That's just my 1/2 cent!

You make a good point of lines 1/2 both being present on jack 1 of the Arris. That may well have been the problem (or not). The telling thing is that when I switched to a plain old generic (yes I'll admit it, chinese) TDM-410P, with the sangoma cables, we got the same issues! So the problem was the cabling, not the Sangoma card. It appears that radiated interference is the problem to the Arris. In both cases I've seen this, simply switching to twisted pair solved the problem. I suspect that the Arris has little to no internal shielding.

 

[boeingpilot]

Ya, the problem with Sangoma is that they are 100% reliable, but configuration can be a problem with newer DAHDI and Asterisk, and even kernel. Long story short I've stopped using in system boards and went to the Vega. Cost wise I believe they're the same (potentially cheaper in some cases) and give you better versatility if you lose your PBX anyway. I couple this with a backup of client systems on rentpbx or my own hyper V cluster and can pass the copper if needed (where copper is desired for the near 100% uptime) over the net.

Yes, if buying new, the Vega may be cost compatible. In my case, I was re-purposing boards from some old trixbox Appliances. No reason to pitch 4 port analog boards with hardware echo cancellation. If I wanted to be totally cheap, I've had good success with the Grandstream GXW-4108's, and they can be had on Amazon for $250.