Hi, we experienced a werid problem that SRX-5400 (cluster) would miss static NAT translation, we have a SBC in trust zone with RFC1918 address, SRX-5400 statically translate this SBC's IP to publically routable IP address, customer sets the SIP trunking pointing to this public IP address, standary stuff and it has been working fine.
We recently had an incident that SIP INVITES sent from our side to customer were silently dropped on customer side, upon troubleshooting, customer confirmed that the INVITES were coming from our side SBC's RFC1918 address therefore dropped by their side firewall. We don't have a way to consistently reproduce this problem, I opened a case with JTAC, JTAC engineer was also puzzled as NAT configuration as well as security policies all look correct, I am wondering can this happen on SRX? I mean, static NAT would either work or not, how could it be that certain translations would be missed?