[Serusers] Processing REFER Messages

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@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@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@66.243.109.99:5060>;tag=204ed7cd9666ebba. To: sip:4075552279@66.236.245.100;tag=EB25EC-B85. Contact: <sip:3212514238@172.31.130.139>. Supported: replaces. Refer-To: <sip:3212814820@sip.mycompany.com>. Referred-By: <sip:3212514238@172.31.130.139>. Call-ID: 13195134-3326638548-685571(a)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.