[Freeswitch-users] Inband SPS/PPS missing because of private/public IP.

Hi, I tried to get video working between one Grandstream and Polycom IP phone with H.264. I'm planning to make freeswitch as SBC for my internal network. However, both proxy media a d pass-thru media are getting one way video. That is Polycom VVX can see Grandstream, not the other way. I sniffer and found out that Polycom is doing inband SPS/PPS, so the first packet or so is for SPS/PPS, without this, the other-side cannot decode the video. But freeswitch media proxy doesn't forward packets to right public address port until it receives packets from the other stream, which will trigger a RTP auto adjustment. I just wondering is there any config to fix this or I have to modify the code? Thanks.