[Asterisk-Users] TE405P and echo

[Steve Kann]

Peter Svensson wrote:

>On Tue, 22 Mar 2005, McQuiggan, Mark  xt46480 wrote:
>
>  
>
>>I am using a SIP softphone (X-lite, SIPPS or Firefly) connected to an
>>Asterisk v 1.0.3 PBX.  The PBX is also connected via a ISDN-PRI crossover
>>cable to a Avaya Definity Generic 3 PBX via a TE405P card.  All outside of
>>the office calls go through the Definity.  Here's the issue:
>> 
>>Calls to internal SIP extensions, Definity extensions, other offices within
>>our private network (through the Definity), and cell phones are great.  When
>>I call outside of the office to POTS lines (like my home), there is a most
>>noticeable echo of my voice.  The party on the line hears no echo.  Any
>>efforts on the configuring the SIP softphones, and within zapata.conf, have
>>been for naught.
>> 
>>Is this problem common for ISDN-PRI connections?
>>    
>>
>
>It is a problem you will see when calling an analogue subscriber over a 
>link with a long latency (such as VoIP). The echo will most probably be 
>generated by a 2- to 4-wire hybrid at the far end. In a pure amalogue/tdm 
>path you would perceive the reflected energy as a plesent sidetone. As 
>soon as the latency increases to 50-100ms the refelcted energy will be 
>perceived as an echo instead.
>
>The options available to you are to live with the echo of your own voice 
>or to insert an echo canceller at the pstn interface. Asterisk includes an 
>echo canceller that may or may not be good enough. It seems to like some 
>pstn interfaces and not others. If the Asterisk echo canceller is not 
>enough you may consider an expensive inline echo canceller. 
>  
>

The definity has echo cancellation. Try turning that on.

-SteveK