Thanks for your reply. I added this, restarted SIP server and restarted the UA but it didn't make any difference. SIP traffic goes to the correct address (10.x.x.x) but RTP traffic was still going to the incorrect address (100.100.x.x) which isn't routable on the network. However, I found net.sip ...

1. Brekeke Product Name and Version: Brekeke SIP Server 2.4.9.0/286.3 2. Java version: 3. OS type and the version: Windows Server 2003 4. UA (phone), gateway or other hardware/software involved: 5. Your problem: Hello. I have a scenario where the UA is behind NAT. The UA is assigned a 100.100.x.x ...