force rtp relay for a specific user or ip

1. Brekeke Product Name and Version: SIP advanced 3.2.4.3

2. Java version:

3. OS type and the version:Win 7

4. UA (phone), gateway or other hardware/software involved:

5. Your problem: I have a UA behind NAT that wont auto relay RTP can I force relay for this user or IP?

create dial plan rule to catch the call from/to this user and set $rtp=on in rule [Deploy Patterns]

but not sure if above setting will solve your issue.

In v3.3.x there are following settings at "RTP" page
maybe it will solve the issue
Port mapping ->source port
Send UA's remote address -> yes