[Asterisk-Users] sip call echo cancellation

[Steve Clark]

Matt Hess wrote:
> I have echo cancellation on in the mp-108 as well as silence 
> suppression.. tinkering with these two settings has not yet yielded any 
> happy results.. which is why I'm asking if the asterisk system has any 
> possible echo cancellation that may help alleviate this issue as it's 
> not only seen on the mp-108 but a few sip phones as well such as a 
> budgetone 2 and an ipdialog.. I have a feeling this has to do with voice 
> output levels.. but it's just a hunch that adding a bit of a reduction 
> to the output audio on the pri trunks will help..
> 
> as I remember it.. if point A calls point B and point A hears echo and 
> point B does not then it's something like an impedance problem on the 
> far end.. or wire center (CO) at that point.. but an impedance mismatch 
> can occur also at a pstn ingress point such as the ILEC side of the pri 
> lines.. or maybe I'm wrong..
> 
> 
> 
> 
> Steve Clark wrote:
> 
> 
>>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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Here is a pretty good write up on it.
http://www.infineon.com/cmc_upload/0/000/012/234/voip_sidec.pdf


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