[Serusers] Yet another ACK issue

Hi all. For some reason this ACK looped and I have no idea why. It's very suspicious that the Record-Route in the second ACK has a branch=0 tag. NOTE: 10.3.0.221 <http://10.3.0.221> is the IP of my ser proxy. It sits behind a Cisco 3600 so the IPs have been rewritten to 10.3.0.221<http://10.3.0.221> . Can anyone give a pointer? Regards, Paul U 2005/04/05 21:06:29.459587 66.90.50.230:54115 <http://66.90.50.230:54115>-> 10.3.0.221:5060 <http://10.3.0.221:5060> ACK sip:8664365708@sipdev.mycompany.com SIP/2.0. Via: SIP/2.0/UDP 172.16.1.42:5060 <http://172.16.1.42:5060> ;branch=z9hG4bK1177883239. From: Paul Hazlett <sip:3212514240@sipdev.mycompany.com>;tag=1697105220. To: <sip:8664365708@sipdev.mycompany.com>;tag=06922fcc. Call-ID: 3209616113(a)172.16.1.42. CSeq: 2301 ACK. Content-Length: 0. . # U 2005/04/05 21:06:29.692031 10.3.0.221:5060 <http://10.3.0.221:5060> -> 10.3.0.221:5060 <http://10.3.0.221:5060> ACK sip:8664365708@sipdev.mycompany.com SIP/2.0. Max-Forwards: 10. Record-Route: <sip:10.3.0.221 <http://10.3.0.221>;ftag=1697105220;lr>. Via: SIP/2.0/UDP 10.3.0.221 <http://10.3.0.221>;branch=0. Via: SIP/2.0/UDP 172.16.1.42:5060 <http://172.16.1.42:5060>;received= 66.90.50.230 <http://66.90.50.230>;branch=z9hG4bK1177883239. From: Paul Hazlett <sip:3212514240@sipdev.mycompany.com>;tag=1697105220. To: <sip:8664365708@sipdev.mycompany.com>;tag=06922fcc. Call-ID: 3209616113(a)172.16.1.42. CSeq: 2301 ACK. Content-Length: 0. P-hint: Local Destination.