[asterisk-dev] ZAP channel hang

Tilghman Lesher tilghman at mail.jeffandtilghman.com
Fri Aug 15 16:33:40 CDT 2008


On Friday 15 August 2008 15:21:04 Paradise Dove wrote:
> I have the same problem and i'm sure that it's not a deadlock and a
> simple "soft hangup" on one of the hung channels will kick them off!
> i can reproduce  it easily,
> one way is to call your box from outside on fxo channels and make your
> scripts to run DISA application and give you an extension tone with
> outside dialing permission, now just dial a number using another fxo
> channel. with this scenario in more than 80% of times after ending the
> conversation conversation, both bridged fxo channels will remain
> connected for ever!!
> the other way is to call a number via fxo channels and then hold the
> call and call another number via fxo channels and then bridge both
> calls together (transfer). also in this scenario the bridged fxo
> channels more than 60% of times will remain hung.
> the same problem exists if you bridge (transfer) two incoming calls
> from fxo channels.

If that is the case, then I believe there is no good way to detect this
problem.  The issue is that the signalling for Loopstart FXO channels
is deficient.  This is normally not a problem, because FXO channels
are rarely bridged with other FXO channels.  Instead, they are usually
bridged with either FXS channels (where the hangup signal is easily
detectable) or SIP or other digital channels, where the hangup signal
is digital in nature and is thus not subject to this problem.

You could certainly try callprogress detection, which attempts to do
a better job of detecting hangups, busy signals, and other exceptional
conditions; however, callprogress is not perfect and may lead to early
termination of calls in certain situations.  The only real solution is to
upgrade to a digitally signalled line (BRI, PRI, or SIP trunking).

-- 
Tilghman



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