<div>Hi, </div>
<div>I run into a weird situation. My media gateay handle voice call with 2 different RTP ports for send & receive</div>
<div> </div>
<div>Here is what happened. (ps: both gateway and FS are all on public IP, no NAT involved)</div>
<div>1. Incoming call INVITE from gateway to FS</div>
<div>Connection Information (c): IN IP4 100.100.100.100 (This is my media gateway IP address)</div>
<div>Media Description, name and address (m): audio 5294 RTP/AVP 18 0 4</div>
<div>2. FS response with session progress with media information</div>
<div>Connection Information (c): IN IP4 200.200.200.200</div>
<div>Media Description, name and address (m): audio 22428 RTP/AVP 0</div>
<div>3. I start to see some RTP traffic exchange between FS and GW</div>
<div>from FS (22428) --> GW (5294)</div>
<div>from GW (5292) --> FS (22428)</div>
<div>please note: the GW use two DIFFERENT PORT for RTP, one for sending and one for receiving</div>
<div>4. For a while (about 5 secs, I think)</div>
<div>The RTP flow change on FS side to become, (there is no RTCP packet during the time)</div>
<div>
<div>from FS (22428) --> GW (5292)</div>
<div>
<div>from GW (5292) --> FS (22428)</div></div></div>
<div>In other word, the FS now sending RTP to 5292 instead of 5294 (which was intended in INVITE SDP message)</div>
<div> </div>
<div>And, of course, I cannot hear the voice on GW side after this.</div>
<div> </div>
<div>Anyone encounter this before? Are there any paramaters that might involved in this auto changing RTP port behavior of FS?</div>
<div> </div>
<div>Any direction for me is appreciated, I will play around with this, and post back my result to community.</div>
<div> </div>
<div>Dan Lan</div>