Still running 1.2.3 here (better luck with VoIP traffic shaping than with 2.x so far.)
This problem went away for a couple of weeks and then re-appeared today. Nothing changed in pfSense config other than some dnsmasq static mappings (which regularly move about for testing.) Running tcpdump on both the NAT target and on pfSense looking for the remote host IP shows the internal host sending keepalives to the ITSP, but nothing coming from them. pfSense firewall rule logs packets that tcpdump does not report on either host:
Act Time If Source Destination Proto
Aug 2 13:37:32 NG0 66.241.X.Y:5060 192.168.X.24:5080 UDP
Aug 2 13:37:30 NG0 66.241.X.Y:5060 192.168.X.24:5080 UDP
Aug 2 13:37:29 NG0 66.241.X.Y:5060 192.168.X.24:5080 UDP
Aug 2 13:37:28 NG0 66.241.X.Y:5060 192.168.X.24:5080 UDP
Aug 2 13:37:21 NG0 66.241.X.Y:5060 192.168.X.24:5080 UDP
Aug 2 13:37:19 NG0 66.241.X.Y:5060 192.168.X.24:5080 UDP
Aug 2 13:37:18 NG0 66.241.X.Y:5060 192.168.X.24:5080 UDP
pfsense:~# tcpdump host 66.241.X.Y
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on vr0, link-type EN10MB (Ethernet), capture size 96 bytes
13:36:19.710032 IP sipx.domain.com.5080 > 66.241.X.Y.5060: SIP, length: 4
13:36:39.717413 IP sipx.domain.com.5080 > 66.241.X.Y.5060: SIP, length: 4
13:36:59.723839 IP sipx.domain.com.5080 > 66.241.X.Y.5060: SIP, length: 4
13:37:19.731218 IP sipx.domain.com.5080 > 66.241.X.Y.5060: SIP, length: 4
13:37:39.737579 IP sipx.domain.com.5080 > 66.241.X.Y.5060: SIP, length: 4
13:37:59.744985 IP sipx.domain.com.5080 > 66.241.X.Y.5060: SIP, length: 4
13:38:19.751407 IP sipx.domain.com.5080 > 66.241.X.Y.5060: SIP, length: 4
13:38:39.758748 IP sipx.domain.com.5080 > 66.241.X.Y.5060: SIP, length: 4
13:38:59.765230 IP sipx.domain.com.5080 > 66.241.X.Y.5060: SIP, length: 4
[root@sipx sipxpbx]# tcpdump host 66.241.X.Y
tcpdump: WARNING: arptype 65535 not supported by libpcap - falling back to cooked socket
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on venet0, link-type LINUX_SLL (Linux cooked), capture size 96 bytes
13:36:19.756734 IP sipx.domain.com.5080 > 66.241.X.Y.sip: SIP, length: 4
13:36:39.757210 IP sipx.domain.com.5080 > 66.241.X.Y.sip: SIP, length: 4
13:36:59.756742 IP sipx.domain.com.5080 > 66.241.X.Y.sip: SIP, length: 4
13:37:19.757247 IP sipx.domain.com.5080 > 66.241.X.Y.sip: SIP, length: 4
13:37:39.756711 IP sipx.domain.com.5080 > 66.241.X.Y.sip: SIP, length: 4
13:37:59.757228 IP sipx.domain.com.5080 > 66.241.X.Y.sip: SIP, length: 4
13:38:19.756763 IP sipx.domain.com.5080 > 66.241.X.Y.sip: SIP, length: 4
13:38:39.757203 IP sipx.domain.com.5080 > 66.241.X.Y.sip: SIP, length: 4
13:38:59.756787 IP sipx.domain.com.5080 > 66.241.X.Y.sip: SIP, length: 4