[Serusers] URGENT! AS5350 <-> SER incompatibility problem

Hi everybody! recently I have been testing calls to/from ISDN with a AS5350. My SER version is 0.8.14 and when I make a call from ISDN towards a SIP UA registered in the SER the problem is that the AS5350 is no aware of Call Release. I explain it in more detail... 1. AS5350 sends an INVITE to the SER with destination number 93222222 2. SER forwards the INVITE to the corresponding SIP UA. 3. UA reponds with a 180 Ringing and it is forwarded to the AS5350 by the SER 4. When I pick up the phone, the SIP UA sends a 200 OK message, which is frowarded by the SER as well. 5. AS5350 replies with a ACK to the 200 OK but beware!! the AS5350 has changed UDP source port!! it is different from the one set in INVITE. 6. The SIP UA hangs up the call by sending a BYE message to the SER (it is Record Routing) 7. The SER forwards the BYE to the AS5350 but with the old UDP port!! 8. AS5350 sends ICMP Destination Unreachable (Cause code: port unreachable) every time that the SER retries the BYE. My guess is that the AS5350 expects the BYE packet through the new UDP port... Has anybody found such a problem? Thanks Victor