[Asterisk-bsd] echo

[Aristedes Maniatis]

We are using a Digium TDM card with 4 FXO ports for connecting to our  
local phone exchange. Running the latest zaptel and asterisk ports.  
Handsets are Cisco/Sipura SPA941 models.

Everything is working very well, and for the most part, phone calls  
clear and of good quality. But every so often a call exhibits a lot  
of echo. It seems that certain destination numbers are more  
susceptible than others to this problem. The echo isn't consistent  
throughout the call, but varies.

I've tried various tweaks to gain, and I guess I could do a little  
more, but it is hard to reproduce the problem every time to see if  
changes help. Is there a more methodical way to do this?

My other question (and a more important one) is: will moving to ISDN  
or a different FXO card help? Does ISDN have echo problems at all, or  
because it is all digital, is this problem completely gone? We are  
thinking of installing Asterisk for our customers, but they will not  
be as tolerant of a little echo as we are. So should we mandate ISDN  
as the best approach?

Otherwise, are other FXO cards better at echo cancellation or is this  
a software feature built into the driver?


Thanks
Ari Maniatis




-------------------------->
ish
http://www.ish.com.au
Level 1, 30 Wilson Street Newtown 2042 Australia
phone +61 2 9550 5001   fax +61 2 9550 4001
GPG fingerprint CBFB 84B4 738D 4E87 5E5C  5EFA EF6A 7D2E 3E49 102A


-------------- next part --------------
A non-text attachment was scrubbed...
Name: PGP.sig
Type: application/pgp-signature
Size: 186 bytes
Desc: This is a digitally signed message part
Url : http://lists.digium.com/pipermail/asterisk-bsd/attachments/20061010/2fec4054/PGP.pgp