[asterisk-users] Asterisk ZAP/DAHDI reads phantom digit on overlap PRI

[Vieri]

Hi,

I've noticed that a small but meaningful quota of calls from my Alcatel PBX to Asterisk are failing.

This does not always happen and it is not easily reproducible but on high traffic I do get a large number of cases.

Example: Alcatel PBX extension 7085 calls Asterisk PBX extension 6145 over a PRI E1 link.

I see this in the Asterisk log:

Dec 14 14:10:31 VERBOSE[11378] logger.c:     -- Accepting overlap call from '7085' to '6145' on channel 1/31, span 1
Dec 14 14:10:31 VERBOSE[5558] logger.c:     -- Starting simple switch on 'Zap/31-1'
Dec 14 14:10:32 DEBUG[5558] chan_zap.c: DTMF digit: 5 on Zap/31-1
Dec 14 14:10:40 DEBUG[5558] chan_zap.c: No such possible extension '61455' in context 'from-alcatel'

Obviously, it's failing because Asterisk is trying to match destination+extra DTMF digit (ie. 6145+5). 

However, noone ever dialed that extra digit! So how did it get there?

I guess I could disable "overlap" in Asterisk but that isn't the right way to go.

What else can I do (where else can I look) to solve this issue?

Thanks,

Vieri