[Asterisk-Users] Cisco 7940G/7960G SIP phones local echo on * box.

[Mitchell S. Sharp]

On Sun, 2004-04-11 at 13:01, Tom wrote:
> Our new * server with Cisco SIP phones is now working pretty well.  But we 
> still have one problem that has not been resolved.
> 
> The Cisco SIP phones have a consistent echo.  It sounds like about a 500ms 
> delay.  This echo is not heard from the POTS side.  It is heard when 
> calling another SIP extension in our office.  We are running 6.3 firmware 
> on the phones.
> 
> Any suggestions would be appreciated.
> 
> Many thanks,
> 
> Tom
> 

Does the echo have any pings associated with it?  I'm running 7960
(firmware 6.3) and it works great with the exception of echo, which has
a noise similar to a sonar ping associated with it.  It does not occur
all the time, and is independent of whether I make the call using IAX2
(through Voice Pulse Connect) or ZAP (PSTN).  I do have echo
cancellation on and have not adjusted rx/tx gain. I tried adjusting it
once with the effect, so reverted it back to what the default was.  I've
tried just about every tweak in the sip.conf, SIPDefault.cnf and
SIP<mac>.cnf files I've been able to come across.  I am running a single
X100P and a TDM400P (with three modules installed).  I will be upgrading
to a T100P and Adtran TA750 this week.

Mitch Sharp