[Asterisk-Users] echo

[Sean Adams]

Read the faq, checked the config files... can't find anything about an 
echo problem like this. Here's what I've got:

4 channel t1 card, span 2 going to channel bank with both fxs and fxo 
lines
Polycom IP600 phones on same LAN with asterisk
iax connection to voicepulse (T1 going out on another router)
Asterisk on a 2.4GHz machine

what I hear:

FXO <-> FXS				no echo at all
FXO or FXS <-> voicepulse	no echo at all
IP600 <-> voicepulse		no echo at all
IP600 <-> FXO or FXS		echo heard by IP600 caller, no echo heard by 
remote party
IP600 <-> IP600			can't get it to work yet - SIP times out (separate 
issue I guess)

I also did a few more tests:

- I made an extension that just does Wait(). Called it from the ip600. 
No echo.

- Used the built in Echo function. I only hear one echo. I measured the 
latency by recording it with a microphone. It is 100ms, which seems a 
bit excessive for ethernet.

The fact that I hear only one echo when doing the Echo test, and no 
echo anywhere except in the IP600 <-> POTS path, would lead me to 
believe that the source of the echo is within asterisk (not in 
transmission or in the phones), and only when bridging SIP<->POTS. Any 
ideas?