[asterisk-users] Bad Echo between SIP calls

[Steve Underwood]

Stephen Davies wrote:
> On 09/06/07, Deepak Naidu <deepak_nai at yahoo.com> wrote:
>> Ya, I have done that, below is zapata.conf.  Also we had an TMP card 
>> with
>> analog lines. & SIP cals were great on them. & now when we switched 
>> over.
>> SIP calls have echo.. which shouldnt be at all.
>
> If you are getting echo on pure SIP to SIP calls, there's no point in
> fiddling around with your zapta.conf.  That file is for configuring
> chan_zap, which is used to talk to Zap/ channels.  Your calls are SIP
> to SIP so the zap channel and your PRI aren't being used at all.
>
> SIP calls are "pure digital" 4 wire lines so no electrical (Hybrid)
> echo will be present.  The phones should not generate echo.  If they
> are, they are presumably nasty phones (what kind are they?) and you
> should get properly made phones.
By this measure most phones are nasty. The handset should be echo 
cancelled, to prevent leakage of the earpiece into the mike. It is 
getting less and less common to do this, now. Polycoms, Sipuras, Snoms, 
you name it, they do it badly. Many are not too annoying until someone 
turns the volume up. Call someone a little hard of hearing and you will 
hear echo.

Steve