SIP in higher education

[Nimal Ratnayake <>]

Hi Steve,

Yes. The same happens for PSTN calls coming through the gateway.  But in
my case, the calls don't drop.  The SIP phone transferring the call and the
calling PBX extension/PSTN user wait in voice state, just as the call 
was put
on hold.

In both cases, the gateway is not setting up the call to the new destination
before sending NOTIFY.

Thanks.

Nimal Ratnayake

Steve Blair wrote:

> Hello Nimal:
>
>   I'm out of the office for out holiday however when I return on Monday I
> will look into this a bit. I think I am having a similar problem. For 
> me a
> call comes in from the PSTN via the Cisco gateway to an IP phone. The
> IP phone blind transfers the call to another IP device and the call 
> drops.
> I'll let you know if I discover anything of interest. May I ask that you
> do the same?
>
> Thanks,Steve
>
> Nimal Ratnayake wrote:
>
> > Apologies for duplicates. previously posted on 
> > .
> >
> > ---------
> >
> > Hi,
> >
> > When a call between a SIP phone and a PBX extension is transfered
> > by the SIP phone to another SIP phone, the SIP gateway does not
> > seem to handle the REFER correctly.  I am using a Cisco 3640 router
> > running IOS 12.3(12).  The call flow is as shown below ( I have
> > omitted the proxy in this picture)
> >
> >
> > SIP                             PBX-GW
> > IP=A.B.C.D                      IP=P.Q.R.S
> > 1602                            3423
> >
> > -------------INVITE--------------->
> > <------------TRYING----------------
> > <------SESSION PROGRESS------------
> > <--------------OK------------------
> > --------------ACK----------------->
> > ----INVITE c=IN IP4 0.0.0.0------->
> > <-----OK c=IN IP4 P.Q.R.S----------
> > --------------ACK----------------->
> > -------REFER Refer-To: 1600------->
> > <-----------Accepted---------------
> > <------------NOTIFY OK-------------
> > -------------- OK----------------->
> >
> >
> > Shouldn't the gateway do an invite to 1600 after receiving REFER
> > *before* sending NOTIFY?
> >
> > Any help or pointers to solve the problem would be appreciated.
> >
> > Thanks.
> >
> > Nimal Ratnayake