Does anybody know if the following behavior is a bug?

UA behind NAT -> SER with MEDIAPROXY -> GATEWAY

U 2005/06/25 22:50:59.020747 200.94.75.6:5060 -> 200.67.33.247:61133
SIP/2.0 183 Session Progress.
Via: SIP/2.0/UDP 172.31.253.127:5060;rport=61133;received=200.67.33.247;branch=z9hG4bK-bb14d3a0.
From: 8183651723 <sip:8183651723@sipsrv.conecta-te.com>;tag=7eee899c25104cbo0.
To: <sip:018183324166@sipsrv.conecta-te.com>;tag=2EC3E224-C59.
Date: Sun, 26 Jun 2005 03:51:20 GMT.
Call-ID: 994132b0-ecde4ec7@172.31.253.127.
Server: Cisco-SIPGateway/IOS-12.x.
CSeq: 101 INVITE.

U 2005/06/25 22:51:06.346082 200.94.75.1:5060 -> 200.94.75.6:5060
SIP/2.0 200 OK.
Via: SIP/2.0/UDP 200.94.75.6;branch=z9hG4bK7176.047de506.0,SIP/2.0/UDP 172.31.253.127:5060;rport=61133;received=200.67.33.247;branch=z9h
G4bK-bb14d3a0.
From: 8183651723 <sip:8183651723@sipsrv.conecta-te.com>;tag=7eee899c25104cbo0.
To: <sip:018183324166@sipsrv.conecta-te.com>;tag=2EC3E224-C59.
Date: Sun, 26 Jun 2005 03:51:20 GMT.
Call-ID: 994132b0-ecde4ec7@172.31.253.127.
Server: Cisco-SIPGateway/IOS-12.x.
CSeq: 101 INVITE.

U 2005/06/25 22:51:06.349202 200.94.75.6:5060 -> 200.67.33.247:61133
SIP/2.0 200 OK.
Via: SIP/2.0/UDP 172.31.253.127:5060;rport=61133;received=200.67.33.247;branch=z9hG4bK-bb14d3a0.
From: 8183651723 <sip:8183651723@sipsrv.conecta-te.com>;tag=7eee899c25104cbo0.
To: <sip:018183324166@sipsrv.conecta-te.com>;tag=2EC3E224-C59.
Date: Sun, 26 Jun 2005 03:51:20 GMT.
Call-ID: 994132b0-ecde4ec7@172.31.253.127.
Server: Cisco-SIPGateway/IOS-12.x.
CSeq: 101 INVITE.

U 2005/06/25 22:51:06.463073 200.67.33.247:61133 -> 200.94.75.6:5060
ACK sip:018183324166@200.94.75.1:5060 SIP/2.0.
Via: SIP/2.0/UDP 172.31.253.127:5060;branch=z9hG4bK-2cfda76b.
From: 8183651723 <sip:8183651723@sipsrv.conecta-te.com>;tag=7eee899c25104cbo0.
To: <sip:018183324166@sipsrv.conecta-te.com>;tag=2EC3E224-C59.
Call-ID: 994132b0-ecde4ec7@172.31.253.127.
CSeq: 101 ACK.

U 2005/06/25 22:51:06.466144 200.94.75.6:5060 -> 200.94.75.1:5060
ACK sip:018183324166@200.94.75.1:5060 SIP/2.0.
Record-Route: <sip:200.94.75.6;ftag=7eee899c25104cbo0;lr=on>.
Via: SIP/2.0/UDP 200.94.75.6;branch=0.
Via: SIP/2.0/UDP 172.31.253.127:5060;received=200.67.33.247;branch=z9hG4bK-2cfda76b.
From: 8183651723 <sip:8183651723@sipsrv.conecta-te.com>;tag=7eee899c25104cbo0.
To: <sip:018183324166@sipsrv.conecta-te.com>;tag=2EC3E224-C59.
Call-ID: 994132b0-ecde4ec7@172.31.253.127.
CSeq: 101 ACK.

U 2005/06/25 22:52:46.932753 200.67.33.247:61133 -> 200.94.75.6:5060
BYE sip:018183324166@200.94.75.1:5060 SIP/2.0.
Via: SIP/2.0/UDP 172.31.253.127:5060;branch=z9hG4bK-fb84955e.
From: 8183651723 <sip:8183651723@sipsrv.conecta-te.com>;tag=7eee899c25104cbo0.
To: <sip:018183324166@sipsrv.conecta-te.com>;tag=2EC3E224-C59.
Call-ID: 994132b0-ecde4ec7@172.31.253.127.
CSeq: 102 BYE.

U 2005/06/25 22:52:46.936356 200.94.75.6:5060 -> 200.94.75.1:5060
BYE sip:018183324166@200.94.75.1:5060 SIP/2.0.
Record-Route: <sip:200.94.75.6;ftag=7eee899c25104cbo0;lr=on>.
Via: SIP/2.0/UDP 200.94.75.6;branch=z9hG4bK4176.978b7dd1.0.
Via: SIP/2.0/UDP 172.31.253.127:5060;received=200.67.33.247;branch=z9hG4bK-fb84955e.
From: 8183651723 <sip:8183651723@sipsrv.conecta-te.com>;tag=7eee899c25104cbo0.
To: <sip:018183324166@sipsrv.conecta-te.com>;tag=2EC3E224-C59.
Call-ID: 994132b0-ecde4ec7@172.31.253.127.
CSeq: 102 BYE.

U 2005/06/25 22:52:46.943252 200.94.75.1:5060 -> 200.94.75.6:5060
SIP/2.0 200 OK.
Via: SIP/2.0/UDP 200.94.75.6;branch=z9hG4bK4176.978b7dd1.0,SIP/2.0/UDP 172.31.253.127:5060;received=200.67.33.247;branch=z9hG4bK-fb84955
e.
From: 8183651723 <sip:8183651723@sipsrv.conecta-te.com>;tag=7eee899c25104cbo0.
To: <sip:018183324166@sipsrv.conecta-te.com>;tag=2EC3E224-C59.
Date: Sun, 26 Jun 2005 03:53:13 GMT.
Call-ID: 994132b0-ecde4ec7@172.31.253.127.

U 2005/06/25 22:52:46.944910 200.94.75.6:5060 -> 200.67.33.247:5060 !!!! The UDP PORT was changed !!!!
SIP/2.0 200 OK.
Via: SIP/2.0/UDP 172.31.253.127:5060;received=200.67.33.247;branch=z9hG4bK-fb84955e.
From: 8183651723 <sip:8183651723@sipsrv.conecta-te.com>;tag=7eee899c25104cbo0.
To: <sip:018183324166@sipsrv.conecta-te.com>;tag=2EC3E224-C59.
Date: Sun, 26 Jun 2005 03:53:13 GMT.
Call-ID: 994132b0-ecde4ec7@172.31.253.127.

The UA retries the BYE again because it didn't receive the 200 OK with the right UDP PORT

U 2005/06/25 22:52:47.429710 200.67.33.247:61133 -> 200.94.75.6:5060
BYE sip:018183324166@200.94.75.1:5060 SIP/2.0.
Via: SIP/2.0/UDP 172.31.253.127:5060;branch=z9hG4bK-fb84955e.
From: 8183651723 <sip:8183651723@sipsrv.conecta-te.com>;tag=7eee899c25104cbo0.
To: <sip:018183324166@sipsrv.conecta-te.com>;tag=2EC3E224-C59.
Call-ID: 994132b0-ecde4ec7@172.31.253.127.
CSeq: 102 BYE.

I'm using
version: ser 0.9.2 (i386/linux)
flags: STATS: Off, USE_IPV6, USE_TCP, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MEM, SHM_MMAP, PKG_MALLOC, FAST_LOCK-ADAPTIVE_WAIT
ADAPTIVE_WAIT_LOOPS=1024, MAX_RECV_BUFFER_SIZE 262144, MAX_LISTEN 16, MAX_URI_SIZE 1024, BUF_SIZE 65535
@(#) $Id: main.c,v 1.197 2004/12/03 19:09:31 andrei Exp $
main.c compiled on 10:21:27 Jun 11 2005 with gcc 3.3

and MEDIAPROXY 1.3.1

I have the ser.cfg for PSTN from ONSIP.org

Regards

Alberto Cruz