[asterisk-dev] Queries regarding Echo Cancellation in Zaptel-1.2.6

[Chan Kwang Mien]

Hi Paul,

Phone A <--> Asterisk PBX 1 <--> Asterisk PBX 2 <--> Phone B

I have 2 questions :

a) Could you enlighten me on how to configure Asterisk to use a
particular codec ? Do I configure it in the Dial command in my
dialplan ?

b) Currently, I have an entry in Asterisk PBX 2 

	exten => 890,1,Dial(Zap/1/891)

and an entry in Asterisk PBX1 

	exten => 891,1,Dial(Zap/4)

Could you tell me how to configure the dial plan to have "loop" calls ?
My understanding is that when Phone B calls Phone A, a voice
path is created. How would it be possible to create a reverse path from
Phone A to Phone B ?

Thank you.


Regards,
Kwang Mien
 


> Hi,
> 
> Chan Kwang Mien wrote:
> > From the translation table, translating ilbc to lpc10 takes the longest
> > time, about 231.
> >
> > Should I configure Asterisk PBX1 to use ibc and Asterisk PBX2 to use
> > lpc10, so that there would be translation time incurred for the Echo ?
> 
> No, just choose a codec with highest cost to convert audio from slin/alaw/ulaw
> which provided by zaptel. As I understand it should be iLBC.
> 
> To use multiple translations you should have additional Asterisk box between two
> existing and have different codecs for Asterisk1 and Asterisk2 to utilize
> intermediate Asterisk as codec translator.
> 
> Anyway, additional translation will introduce additional 20-30 ms (due to
> encoding/decoding).
> 
> Also, you could make "looped" calls (coming from Asterisk1 to Asterisk2, then
> from Asterisk2 to Asterisk1, then again to Asterisk2, and so on) where each call
> direction uses different codec (i.e. call from Asterisk1 to Asterisk2, for
> example, uses iLBC, from Asterisk2 to Asterisk1 - GSM).
> 
> 
> WBR,
> Paul.
> 
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