<div dir="ltr">Hi,<div><br></div><div>After asking many questions, I haven't got any clues about how Kamailio handles INVITE message by default, in terms of modifying c= line in SDP</div><div><br></div><div>According to rtpproxy flow <a href="http://kamailio.org/docs/ser-getting-started/SER-GettingStarted.pdf">http://kamailio.org/docs/ser-getting-started/SER-GettingStarted.pdf</a></div>
<div><br></div><div>When client register, SIP proxy will call nat_uac_test() to detected if client is NATed or not, then save this info.</div><div><br></div><div>When client A calls client B, the INVITE message will go through SIP proxy. Here the SIP proxy can do 3 things (as in section "INVITEs behind NAT" in the pdf). </div>
<div><br></div><div>1. Add an SDP command direction:active to the SDP content</div><div>2. Change the c= line to a.b.c.d</div><div>3. Force RTP to go through a proxy by changing the c-line to c=IN IP4 address-of-proxy and the m-line to</div>
<div>m=audio port-on-proxy RTP/AVP 0 101. </div><div><br></div><div>When will SER do 2, 3 ?<br clear="all"><div><br></div>-- <br><span style>Khoa Pham</span><br style><span style>HCMC University of Science</span><br style>
<span style>Faculty of Information Technology</span><br>
</div></div>