asterisk users - Jan 2006 - Dynamically disabling echo cancellation (Zap).

Hi!  For reasons that I won't bore people with, I'd like to disable echo
cancellation on-the-fly, depending on which DID a call came in on.  I've
seen things like spandsp disable EC for faxes, so I know it's possible. 
Any idea where to start looking?  (I assume I'll have to make a helper
application of some sort to be called externally, and that's fine.)

Thanks!

-Ken

P.S.  If this question is more appropriate for a developer's list, please
let me know.

You can do a down and dirty test to see if it will work.  You can
record the start of a fax tone into a file.

Then after you answer the channel play the file. The 'special tone' will
cancel all of the Ecs on the line.

Its dity but will work in a pinch.

> -----Original Message-----
> From: asterisk-users-bounces@lists.digium.com 
> [mailto:asterisk-users-bounces@lists.digium.com] On Behalf Of 
> Ken D'Ambrosio
> Sent: Thursday, January 26, 2006 12:00 PM
> To: asterisk-users@lists.digium.com
> Subject: [Asterisk-Users] Dynamically disabling echo 
> cancellation (Zap).
> 
> Hi!  For reasons that I won't bore people with, I'd like to 
> disable echo cancellation on-the-fly, depending on which DID 
> a call came in on.  I've seen things like spandsp disable EC 
> for faxes, so I know it's possible. 
> Any idea where to start looking?  (I assume I'll have to make 
> a helper application of some sort to be called externally, 
> and that's fine.)
> 
> Thanks!
> 
> -Ken
> 
> P.S.  If this question is more appropriate for a developer's 
> list, please let me know.
> 
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> Hi!  For reasons that I won't bore people with, I'd like to disable
> echo cancellation on-the-fly, depending on which DID a call came in
> on.  I've seen things like spandsp disable EC for faxes, so I know
> it's possible. Any idea where to start looking?  (I assume I'll
have
> to make a helper application of some sort to be called externally,
> and that's fine.)    
If you are using bristuff you could use the m option
Dial(Zap/g1m/Number) in order to get rid of rxgain/txgain and AFAIK echo
cancellation. This has been built into bristuff esp. for faxes etc.

Regards,
  JP