[Asterisk-Users] Sangoma A200 preventing Zap channels from disconnecting immediately after PSTN line hangs up (getting empty voicemails)

[Mike Garey]

On 4/26/06, Eric ManxPower Wieling <eric at fnords.org> wrote:
> Are you in the USA or Canada?

I'm in Canada. Toronto, Ontario to be exact.  And it was on a local
ontario Asterisk users group where other people with Sangoma A200
cards mentioned they were having the same problem.. So it could be
something related to both the Sangoma A200 card and my local telco
(Bell Canada).

On 4/26/06, Eric ManxPower Wieling <eric at fnords.org> wrote:
> John Novack wrote:
> >
> >
> > Mike Garey wrote:
> >
> >> well, the problem isn't that the card doesn't detect a disconnect,
> >> it's that it doesn't detect it immediately (or at least within a short
> >> period).
> > Odds are that is the telco, and not the Sangoma or Digium card. That is
> > quite normal for a 10-30 second delay. Not all telco CO's send an
> > immediate pulse when the caller hangs up.
> >
> > Is there no way to detect 5-6 seconds of silence by Asterisk?
>
> This is from /path/src/asterisk/configs/voicemail.conf.sample.  Amazing
> how much good stuff is in that directory.  Especially handy to read
> after a significant upgrade (i.e. 1.0.x to 1.2.x)
>
> ; How many seconds of silence before we end the recording
> maxsilence=10
> ; Silence threshold (what we consider silence, the lower, the more
> sensitive)
> silencethreshold=128

the maxsilence setting doesn't really help, as I believe that only
limits how long we record for after voicemail has already started and
silence is detected.  I don't want voicemail to record anything at all
if the call has been disconnected before the voicemail prompt starts.

What I don't understand is that this works fine on many regular
telephone answering machines, which are _much_ less advanced than
asterisk. If they can do it, why can't asterisk?  I mean, if I call my
home line and wait for the answering machine message to kick in, then
hangup right before it starts recording, I don't end up with an empty
message, the system just disconnects me.

I'm starting to get a lot of complaints about this, and I can totally
understand where my users are coming from - it's annoying and a waste
of time to have to go through 3 or 4 empty messages.

I guess I just need to isolate whether this is an asterisk problem or
a Sangoma problem, so I can figure out what step to take next. 
Thanks,

Mike