[Asterisk-Users] Weird ring back

[dbruce]

The weird ring back is a symptom of a problem with SIP message
syncronization (the equivilent of PSTN glare).

1) phone sends INVITE
2) * accepts the call, sends appropriate progress messages, then a 200 OK
3) the conversation proceeds
4) the caller and callee hangs up
5) * sends a BYE to the phone and the phone sends a BYE to *
6) The phone, because it is busy sending a signalling message, delays
processing the received BYE message.
7) * resends the BYE, as it has not received an ACK (has not yet sent an OK
to the phones BYE or stopped the RTP stream)
8) the phone, which is now "on hook", receives the new BYE and the RTP.
9) The phone, still receiving RTP on a call with an unacknowledged BYE, has
no audio device to output the received audio, so it reestablishes its audio
path by ringing.
10) by the time the phone is answered, * has stopped the RTP stream and
destroyed the call, and the state of the phone is out of sync.
11) The answered call is DEAD... The phone thinks that there is a call but
the call no longer exists or is handled by *.



----- Original Message -----
From: "Kristof Hardy" <kristof.hardy at catsanddogs.com>
To: "Asterisk Users Mailing List - Non-Commercial Discussion"
<asterisk-users at lists.digium.com>
Sent: Monday, July 04, 2005 12:14 PM
Subject: Re: [Asterisk-Users] Weird ring back


> David Wilson wrote:
> > I have a weird thing happening sometimes with users calling from a
> > GrandStream phone through Asterisk onto a PSTN.
> > Sometimes after a user hangs up a call on a GrandStream phone the phone
> > starts ringing after a couple seconds.
> > When the call is answered there is no one there.
>
> What phone are you using? A GXP-2000 or other model? I received notice
> of someone experiencing a sporadic 'ring' on his phone, but I'm not sure
> it was after haning up a call..
>
> Do you use CDR logging (to mysql?), if yes, do you find anything in
> there about this call?
>
> Maybe try searching through the asterisk logfile for records of this call?
>
>
> Cheers,
>
> Kristof.
>
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