SIP in higher education

[Jeremy George <>]

Steve,

  Does it make a difference whether the IP devices are all Cisco or
not?  I _seem_ to recall blind transfers work in all Cisco mode but
not necessarily otherwise.

- Jeremy


On Thu, 24 Nov 2005, Steve Blair wrote:

> Date: Thu, 24 Nov 2005 06:49:12 -0500
> From: Steve Blair 
> <>
> Reply-To: 
>
> To: 
>
> Subject: Re: [sip.edu] Cisco gateway not handling REFER correctly?
>
>
>
> 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