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Subject: SIP in higher education

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Re: [] Cisco gateway not handling REFER correctly?

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  • From: Nimal Ratnayake <>
  • To: , Steve Blair <>
  • Subject: Re: [] Cisco gateway not handling REFER correctly?
  • Date: Thu, 24 Nov 2005 18:08:50 +0600

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.


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?


Nimal Ratnayake wrote:

Apologies for duplicates. previously posted on



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)

1602 3423

<------SESSION PROGRESS------------
----INVITE c=IN IP4>
<-----OK c=IN IP4 P.Q.R.S----------
-------REFER Refer-To: 1600------->
<------------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.


Nimal Ratnayake

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