[Serusers] Faulty Transaction Matching (or something)

Hi All. Below is a SIP call log when a user dialed *98 which doesn't exist. So SER properly replied with a 404 and the SIP UA ACKed it, but then SER did something very strange -- it attempted to send the ACK to itself and caused a loop. I cannot understand why. SER only does this occasionally. Am I missing something? Regards, Paul U 2005/04/09 15:06:17.652209 69.164.35.165:5060 <http://69.164.35.165:5060>-> 10.3.0.221:5060 <http://10.3.0.221:5060> INVITE sip:*98@sipdev.mycompany.com SIP/2.0. Via: SIP/2.0/UDP 69.164.35.165:5060 <http://69.164.35.165:5060> ;branch=z9hG4bK3099039843. From: Demo User <sip:3212514237@sipdev.mycompany.com>;tag=834547832. To: <sip:*98@sipdev.mycompany.com>. Call-ID: 2364611513(a)69.164.35.165. CSeq: 1301 INVITE. Contact: <sip:3212514237@69.164.35.165:5060>. Proxy-Authorization: Digest username="3212514237", realm=" sipdev.mycompany.com <http://sipdev.mycompany.com>", nonce="425828d534596342b1ca79431668dc1f45f1d8e8", uri=" sip:*98@sipdev.mycompany.com", response="397365c1a896effa0671df07b27d3e39", algorithm=MD5, cnonce="9bd3799c3cdd94cb2204901c2db4ff8b", qop=auth, nc=0000020a. max-forwards: 70. Allow: INVITE, ACK, CANCEL, BYE, REFER, NOTIFY. Content-Type: application/sdp. Content-Length: 178. . v=0. o=- 674 3207 IN IP4 69.164.35.165 <http://69.164.35.165>. s=-. c=IN IP4 69.164.35.165 <http://69.164.35.165>. t=0 0. m=audio 13456 RTP/AVP 18 0 8 2 4 101. a=rtpmap:101 telephone-event/8000. a=fmtp:101 0-15. a=ptime:20. # U 2005/04/09 15:06:17.658659 10.3.0.221:5060 <http://10.3.0.221:5060> -> 69.164.35.165:5060 <http://69.164.35.165:5060> SIP/2.0 404 User Not Found. Via: SIP/2.0/UDP 69.164.35.165:5060 <http://69.164.35.165:5060> ;branch=z9hG4bK3099039843. From: Demo User <sip:3212514237@sipdev.mycompany.com>;tag=834547832. To: <sip:*98@sipdev.mycompany.com>;tag=cdbfe46960d7566fcbe09f199f2b328d.2395 . Call-ID: 2364611513(a)69.164.35.165. CSeq: 1301 INVITE. Content-Length: 0. # U 2005/04/09 15:06:26.995837 69.164.35.165:5060 <http://69.164.35.165:5060>-> 10.3.0.221:5060 <http://10.3.0.221:5060> ACK sip:*98@sipdev.mycompany.com SIP/2.0. Via: SIP/2.0/UDP 69.164.35.165:5060 <http://69.164.35.165:5060> ;branch=z9hG4bK3099039843. From: Demo User <sip:3212514237@sipdev.mycompany.com>;tag=834547832. To: <sip:*98@sipdev.mycompany.com>;tag=cdbfe46960d7566fcbe09f199f2b328d.2395 . Call-ID: 2364611513(a)69.164.35.165. CSeq: 1301 ACK. Content-Length: 0. . # U 2005/04/09 15:06:27.230645 10.3.0.221:5060 <http://10.3.0.221:5060> -> 10.3.0.221:5060 <http://10.3.0.221:5060> ACK sip:*98@sipdev.mycompany.com SIP/2.0. Max-Forwards: 10. Record-Route: <sip:10.3.0.221 <http://10.3.0.221>;ftag=834547832;lr>. Via: SIP/2.0/UDP 10.3.0.221 <http://10.3.0.221>;branch=0. Via: SIP/2.0/UDP 69.164.35.165:5060 <http://69.164.35.165:5060> ;branch=z9hG4bK3099039843. From: Demo User <sip:3212514237@sipdev.mycompany.com>;tag=834547832. To: <sip:*98@sipdev.mycompany.com>;tag=cdbfe46960d7566fcbe09f199f2b328d.2395 . Call-ID: 2364611513(a)69.164.35.165. CSeq: 1301 ACK. Content-Length: 0. P-hint: Local Destination.