[Asterisk-Users] asterisk em echo problem

[Bill Lattner]

We are having echo problems with 1 in 6 calls on our Asterisk system.  It's a 
one 
sided echo, users hear their own voice delayed about half a second and slightly 
attuneated.  Without the echo canceller in Asterisk enabled echo problems occur 
on 1 in 3 calls and is much worse.  We have a trouble ticket open with SBC and 
have thus far failed to find a cause (they do not believe that it is being 
caused by 
hybrid imbalances however).  I would like to know any advice you would have 
that does not require Asterisk or Zaptel to be recompiled.  Our details are as 
follows:

-T1 using EM wink
-Polycom 300's and 500's (SIP phones with g.711)
-Digium TE110p (has it's own interrupt)
-echocancel = yes (have also tried 32, 64, 128, 256; 128 works best so far)
-echotraining = 400 (have also tried 200, 400, 800; seems to have no effect, 
the wiki says the max is higher but asterisk does not like anything higher than 
999ms)
-Asterisk Ver. 1.0.7 running on P4 3.0Ghz with 2Gb ram and Asus p4p800 mb

EM takes some time for call setup, is Asterisk's echo canceller training 
during 
this time?  If so would switching to PRI alleviate the problem?

Thanks for any help you can offer,
-Bill Lattner
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[Asterisk-Users] Asterisk and echo

[Aldo Bergamini]

Since a couple of days I using an Asterisk server. I noticed something
obvious to anybody dealing with telephony since any longer time than
myself; echo is nasty...

Is it correct to say that the difference between a conversation between
SIP phone, Asterisk, an ISDN BRI line and a GSM phone is entirely
digital, whereas I do have a remote analog portion of the sound link only
if I dial an analog landline subscriber?

At times I do hear a bad echo of my own voice when calling old POTS users
(while they do not report any echo), while so far I did not have any echo
with cellphones.

Can I do anything with echo suppression on my side? Is it beyond the
features of my cheap (convenient..) Fritz PCI card?

Thanks,
Aldo


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