[Asterisk-Users] asterisk e&m 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 E&M 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

E&M 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