[Serusers] SER 0.8.12, Polycom 300, and ignored CANCEL messages

Anyone else seeing problems with Polycom 300 phones ignoring CANCEL messages from a SER proxy? I've got a number of SER proxies (running 0.8.12) that are receiving CANCEL messages and passing them on to the Polycom phone, but all indications are that the phone is just ignoring them (as it continues to ring). Below is an example capture: U 2004/11/08 15:10:32.802663 172.16.22.25:5060 -> 130.110.72.16:5060 SIP/2.0 180 Ringing..Via: SIP/2.0/UDP 130.110.72.16..From: "Interaction Cen ter" <sip:8475787000@GLCU.ORG;type=ICConnectionCall>;tag=8500..To: <sip:187 42@172.16.22.25:5060>;tag=585588F8-A212D515..CSeq: 1 INVITE..Call-ID: 198f7 c0ca5c28e7f59759c1f1c024617@130.110.72.16..Contact:<sip:18742@172.31.22.12> ..Record-Route: <sip:18742@172.16.22.25;ftag=8500;lr=on>..User-Agent: Polyc omSoundPointIP-SPIP_500-UA/1.1.0..Content-Length: 0.... U 2004/11/08 15:10:47.634541 130.110.72.16:1136 -> 172.16.22.25:5060 CANCEL sip:18742@172.16.22.25:5060 SIP/2.0..To: <sip:18742@172.16.22.25:506 0>..From: "Interaction Center" <sip:8475787000@GLCU.ORG;type=ICConnectionCa ll>;tag=8500..Via: SIP/2.0/UDP 130.110.72.16..CSeq: 1 CANCEL..Call-ID: 198f 7c0ca5c28e7f59759c1f1c024617@130.110.72.16..User-Agent: ININ-EICSRVR01-9987 9649..Content-Length: 0.... U 2004/11/08 15:10:47.634635 172.16.22.25:5060 -> 172.31.22.12:5060 CANCEL sip:18742@172.31.22.12 SIP/2.0..Max-Forwards: 10..Record-Route: <sip :18742@172.16.22.25;ftag=8500;lr=on>..To: <sip:18742@172.16.22.25:5060>..Fr om: "Interaction Center" <sip:8475787000@GLCU.ORG;type=ICConnectionCall>;ta g=8500..Via: SIP/2.0/UDP 172.16.22.25;branch=z9hG4bK7377.54324bd5.0..Via: S IP/2.0/UDP 130.110.72.16..CSeq: 1 CANCEL..Call-ID: 198f7c0ca5c28e7f59759c1f 1c024617@130.110.72.16..User-Agent: ININ-EICSRVR01-99879649..Content-Length : 0.... U 2004/11/08 15:10:47.986990 172.16.22.25:5060 -> 172.31.22.12:5060 CANCEL sip:18742@172.31.22.12 SIP/2.0..Max-Forwards: 10..Record-Route: <sip :18742@172.16.22.25;ftag=8500;lr=on>..To: <sip:18742@172.16.22.25:5060>..Fr om: "Interaction Center" <sip:8475787000@GLCU.ORG;type=ICConnectionCall>;ta g=8500..Via: SIP/2.0/UDP 172.16.22.25;branch=z9hG4bK7377.54324bd5.0..Via: S IP/2.0/UDP 130.110.72.16..CSeq: 1 CANCEL..Call-ID: 198f7c0ca5c28e7f59759c1f 1c024617@130.110.72.16..User-Agent: ININ-EICSRVR01-99879649..Content-Length : 0.... U 2004/11/08 15:10:48.124132 130.110.72.16:1136 -> 172.16.22.25:5060 CANCEL sip:18742@172.16.22.25:5060 SIP/2.0..To: <sip:18742@172.16.22.25:506 0>..From: "Interaction Center" <sip:8475787000@GLCU.ORG;type=ICConnectionCa ll>;tag=8500..Via: SIP/2.0/UDP 130.110.72.16..CSeq: 1 CANCEL..Call-ID: 198f 7c0ca5c28e7f59759c1f1c024617@130.110.72.16..User-Agent: ININ-EICSRVR01-9987 9649..Content-Length: 0.... -- Jamin W. Collins "Never underestimate the power of very stupid people in large groups." -- John Kenneth Galbraith