asterisk users - Oct 2004 - sip call echo cancellation

I haven't found much info that stands out to me in regards to echo 
cancellation in sip to sip calls..

My setup is this..
I have a key system connection to an audiocodes mp-108 which connects to 
asterisk via sip and asterisk passes the call over to a ser proxy and 
ser passes the call to either an internet voice terminator for long 
distance or a local pstn gateway.. the local gateway is a lucent max tnt 
with 10.1.1 software load.. it dumps the sip calls onto pri trunks..

I'm still getting feedback from the office as to whether or not echo is 
heard on local or long distance.. incoming outgoing etc.. so I know 
which part to troubleshoot.. if the echo is on egress or ingress.. I 
know it isn't the local key system with echo as it's almost all digital 
apart from the analog connection from key system to audiocodes sip 
gateway as I also have a few ip phones which connect to asterisk that 
experience similar echo issues.. remote callers don't seem to hear any 
echo so it would appear to be an impedance issue somewhere remotely on 
the pstn..

My thinking is that the mismatch may be on the local tnt gateway but I'm 
not 100% positive of that.. I know ingress calls to the sip network have 
echo and those flow through the pri lines to the tnt so I'm starting 
there with that gateway but I'm looking for something possibly on 
asterisk that can help with pure sip call echo cancellation.. does 
anyone have any ideas as to what may help?



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Matt Hess wrote:
> I haven't found much info that stands out to me in regards to echo 
> cancellation in sip to sip calls..
> 
> My setup is this..
> I have a key system connection to an audiocodes mp-108 which connects to 
> asterisk via sip and asterisk passes the call over to a ser proxy and 
> ser passes the call to either an internet voice terminator for long 
> distance or a local pstn gateway.. the local gateway is a lucent max tnt 
> with 10.1.1 software load.. it dumps the sip calls onto pri trunks..
> 
> I'm still getting feedback from the office as to whether or not echo is
> heard on local or long distance.. incoming outgoing etc.. so I know 
> which part to troubleshoot.. if the echo is on egress or ingress.. I 
> know it isn't the local key system with echo as it's almost all
digital
> apart from the analog connection from key system to audiocodes sip 
> gateway as I also have a few ip phones which connect to asterisk that 
> experience similar echo issues.. remote callers don't seem to hear any 
> echo so it would appear to be an impedance issue somewhere remotely on 
> the pstn..
> 
> My thinking is that the mismatch may be on the local tnt gateway but
I'm
> not 100% positive of that.. I know ingress calls to the sip network have 
> echo and those flow through the pri lines to the tnt so I'm starting 
> there with that gateway but I'm looking for something possibly on 
> asterisk that can help with pure sip call echo cancellation.. does 
> anyone have any ideas as to what may help?
> 
> 
> 
> 
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In the MP-108 try turning on Silence Suppression and Echo Cancellation.

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