[Asterisk-Users] False Zap answer problem

[Soner Tari]

Hi All,

I am experiencing a very strange problem. I call the FXO channels (Zap/2 and 
3) almost at the same time, and then hang both up. The operator extension is 
Zap/6, and after the greeting message Zap/6 starts to ring (there is no 
disconnect supervision here, and I disabled the busy detect for hangup 
detection, so the outside lines stay open until Asterisk hangs them up).

As you can see on the following CLI section, when the VoiceMail promt starts 
to play for Zap/2, the system thinks that Zap/6-2 has answered the Zap/3, 
when in fact nobody answers it:

    -- Hungup 'Zap/6-1'
    -- Executing VoiceMail("Zap/2-1", "u0") in new stack
    -- Playing 'vm-theperson' (language 'tr')
    -- Zap/6-2 answered Zap/3-1

I can very easily replicate this (did it 3 times).

Where should I look for the source of this problem? Is it the TDM card or 
the Asterisk? How does Asterisk know if a line has been answered on a TDM 
card? This seems like some kind of cross-talk between the two FXO channels, 
but it's really strange. Has anybody had a similar problem?

Of course, the workaround is to use some sort of hangup detection on outside 
lines, but I was having false hangup problems with busy detect, thus 
disabled it and noticed this problem (and see my above comment on disconnect 
supervision here).

I have 2x TDM cards (version E/F) with 3x FXO and 4x FXS modules on each.

Asterisk version is:
Asterisk CVS-HEAD built by root at asterisk on a i686 running Linux on 
2005-08-10 22:55:45 UTC

I have echocancel and echocancelwhenbridged enabled. (Could it be the 
echocanceller?)

I would appreciate any help,
Soner