Hi all, found our that UDP/53 port is prioritized on most mobile operators as DNS traffic. It would be really effective to be able to use only port 53 udp for incoming RTP traffic of FS while acting as Media Relay. I tried with: <param name="rtp-start-port" value="53"/> <param name="rtp-end-port" value="53"/> But i got error: 2010-03-27 15:54:57.566241 [WARNING] switch_core_port_allocator.c:74 Rounding odd start port 53 to 54 2010-03-27 15:54:57.566241 [WARNING] switch_core_port_allocator.c:78 Rounding odd end port 53 to 52 2010-03-27 15:54:57.566241 [CRIT] sofia_glue.c:712 No RTP ports available! 2010-03-27 15:54:57.566241 [ERR] sofia_glue.c:1203 sofia/internal/sip:546547426@109.112.56.148:39664 I/O Error If FS would be able to support a mode where it can receive multiple RTP streams coming from different peers on the same local port it would be very useful for mobile voip environment. Fabio