We took the plunge this week and deployed Asterisk to over 30 workstations. We’re using a TDM2400 with 12 FXO channels on a Dell 2850. The card is on a clean IRQ and runs without misses. The handsets are all Polycoms, ranging from 301s to IP4000’s.
Everything is working great with the exception of an occasional clipping/choppy PSTN call. The choppiness is only heard on our side, the outside caller doesn’t seem to notice at all. I thought it was isolated to a particular Zap channel; but that theory evaporated today when it presented itself on a different one.
All the SIP to SIP calls are amazingly clean.
Bandwidth is not an issue.
The only thread I can pull from this is that it is isolated to a few phone #'s, but its not a rule, it occured yesterday while I was on a call home, when its normally crystal clear.
Would the echo cancellation module be contributing to this?
Is it possible I have a bad FXO module (4 channels each on the TDM2400)
Ideas anyone?
I had the same problem with my TDM2400 and the problem was the hardware echo can. After removing it, the sound was clear.
I then replaced my TDM2400 with an A200 with hardware echo can. No more problem.
I did a RMA for the echo can but i haven’t tested the new one.
[quote=“Dimitripietro”]I had the same problem with my TDM2400 and the problem was the hardware echo can. After removing it, the sound was clear.
I then replaced my TDM2400 with an A200 with hardware echo can. No more problem.
I did a RMA for the echo can but i haven’t tested the new one.[/quote]
Was it as I described? Its very hit and miss…
What are the consequences of removing the module? Will there be echo or will the software cancelling take over?
Exact same symptom. Sond is choppy. It’s like the sound ins skiping. The discussion is still possible thought.
The consequence was clear sound 
I didn’t had any echo. The software echo can was doing the job.
[quote=“Dimitripietro”]Exact same symptom. Sond is choppy. It’s like the sound ins skiping. The discussion is still possible thought.
The consequence was clear sound I didn’t had any echo. The software echo can was doing the job.[/quote]
This kinda sucks. Why sell the TDM with the echo module in the first place?
I have both a TDM400 and a TDM2400, I can’t say I’m very pleased with either.
Because is needed a working solution for a system that was already in production and because the system is located at 5 hour in car of me.
I received the new echo can last week. I didn’t had the time to test it yet.
I’ve been a regular in the Digium support queue these days. Here’s a recap of what’s been changed and what works/didn’t.
1- Built latest and greatest Zaptel. 1.2.9.1 … no change in choppiness
2- Digium ssh’ed to our * box and played with some gains in the zconfig.h.
- matters were made much worse, think “Timmy stuck in a well” degree of echo
3- Rebuilt the OEM Zaptel 1.2.9.1 and enabled #define ECHO_CAN_MG2 in zconfig.h
Turned zapata.conf gains down to 1.0 tx and 1.0 rx
Echo and chop seems to have stopped.
I hope this helps the next person with a TDM2400 + echo can.
I’ve since RMA’d one FXO module, it was inducing all sorts of static and noise on a certain pair of Zap channels, in my case 16 and 17. This module was responsible for all sorts of nasty that seems to have gone away now.
The choppiness persists, complimented by a what was described as a turntable playing a damaged record… poping, hissing and “squishing”.
Upon the advice received in this post, I went in to the office today and pulled the echo cancellation module on this TDM 2400 followed by an immediate improvement in call quality. I’ll be calling Digium on Monday to see what’s up.
The echo was still quite present despite a few zapata.conf tweaks, so I pulled down the lastest Zaptel 1.2.10 and compiled with the stock Makefile and it would seem things are MUCH better now as compared to Zaptel 1.2.9.1 with MG2.
Anyways, this is a trade-off between an occasional bad choppy call and one that echos for the half second or so… I think our staff will be happier with the latter.
We’ll see how this plays out during the week. Updates to follow.
I am also having the cho.p. issue. I did the following mod suggested on another forum:
In your modprobe.conf add
options wctdm24xxp vpmsupport=0
and stop amportal and rmmod all zaptel services
If the “choppiness” goes away then it is because you are over driving the echo cancel (that expensive modules wants clean lines)
I suggest also running 0 for both tx and rx gain just for testing. If all your choppiness goes away you may have to look into software only compression or add a pre-amp block to your PSTN lines so that when you test with your CO’s milliwatt line your tdm card will be balanced before having to use tx rx gain.
I think this option turns off the hw echo cancellation??? Anyway the jury is out until I get the whole staff in on Monday. My initial report is that the choppy audio is gone. Why did I spend that extra $$$ for ec???
Vince