[Serusers] Processing REFER Messages

[Java Rockx]

Hi All.

I've got a question about handling REFER messages. Below is a REFER message 
that my Grandstream GXP2000 phone generated when I transferred a call to 
another SIP phone on the same SER proxy.

The problem is that SER did a lookup('location') and couldn't find the phone 
number in the subscriber table, so it routed the message to the PSTN 
gateway.

SER should have looked at the Refer-To header to get the actual destination 
of the message.

How can I get SER to handle this message correctly? Should REFER messages 
hit the lookup('location') function in my ser.cfg script?

NOTE: my SER proxy sits behind a Cisco 3600 so the ALG functionality has 
altered the IP. The message shows my SER server as IP address
10.3.0.221<http://10.3.0.221>

Regards,
Paul

U 2005/06/01 14:22:24.073518 66.90.46.29:5060 <http://66.90.46.29:5060> -> 
10.3.0.221:5060 <http://10.3.0.221:5060>
REFER sip:4075552279 at 66.243.109.99:5060 SIP/2.0.
Via: SIP/2.0/UDP 172.31.130.139 <http://172.31.130.139>
;branch=z9hG4bK09ff837994d9e898.
Route: <sip:4075552279 at 10.3.0.221:5060;nat=yes;ftag=204ed7cd9666ebba;lr>.
Route: <sip:216.229.127.60:5060 <http://216.229.127.60:5060>;lr>.
From: 3212514238 <sip:3212514238 at 66.243.109.99:5060>;tag=204ed7cd9666ebba.
To: sip:4075552279 at 66.236.245.100;tag=EB25EC-B85.
Contact: <sip:3212514238 at 172.31.130.139>.
Supported: replaces.
Refer-To: <sip:3212814820 at sip.mycompany.com>.
Referred-By: <sip:3212514238 at 172.31.130.139>.
Call-ID: 13195134-3326638548-685571 at 66.243.109.99.
CSeq: 51906 REFER.
User-Agent: Grandstream GXP2000 1.0.1.8 <http://1.0.1.8>.
Max-Forwards: 70.
Allow: 
INVITE,ACK,CANCEL,BYE,NOTIFY,REFER,OPTIONS,INFO,SUBSCRIBE,UPDATE,PRACK.
Content-Length: 0.
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