[Asterisk-Users] Re: echo

[Stephen R. Besch]

Comments inline
> 
> Read the faq, checked the config files... can't find anything about an 
> echo problem like this. Here's what I've got:
> 
> 4 channel t1 card, span 2 going to channel bank with both fxs and fxo lines
> Polycom IP600 phones on same LAN with asterisk
> iax connection to voicepulse (T1 going out on another router)
> Asterisk on a 2.4GHz machine
> 
> what I hear:
> 
> FXO <-> FXS                no echo at all
	This is the expected result:  Straight analog - delay too short to hear 
any echo.

> FXO or FXS <-> voicepulse    no echo at all
	Expected result: Local analog loop too short for echo.  Hybrid echo at 
FXS/FXO to digital would be heard by remote party if VP didn't do echo 
cancellation, which they no doubt do.

> IP600 <-> voicepulse        no echo at all
	Expected result: Fully digital to VP. Echo generated at VP termination 
would be heard by remote party but will no doubt have been removed by VP.

> IP600 <-> FXO or FXS        echo heard by IP600 caller, no echo heard by 
> remote party
	Expected result: IP600 listening to itself talk through imbalanced 
hybrid at FXO/FXS. Remote termination should hear nothing. * echo 
cancellation must be enabled to remove this.  See many many posts on the 
subject and also check out the WIKI.

> IP600 <-> IP600            can't get it to work yet - SIP times out 
> (separate issue I guess)
	Don't know about this one.  Probably a sip.conf or exten.conf error.
> 
Stephen R. Besch