[SR-Users] How does Kamailio handle INVITE message by default ?

[Daniel-Constantin Mierla]

Hello,

On 3/6/13 1:54 PM, Khoa Pham wrote:
> Hi,
>
> 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
>
> According to rtpproxy flow 
> http://kamailio.org/docs/ser-getting-started/SER-GettingStarted.pdf
>
> When client register, SIP proxy will call nat_uac_test() to detected 
> if client is NATed or not, then save this info.
>
> 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).
>
> 1. Add an SDP command direction:active to the SDP content
> 2. Change the c= line to a.b.c.d
> 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
> m=audio port-on-proxy RTP/AVP 0 101.
>
> When will SER do 2, 3 ?
2 and 3 are done usually when using rtpproxy to relay rtp packets (e.g., 
via rtpproxy_manage() function), or using various functions related to 
sdp updating from nathelper/rtpproxy/siputils or mangler module.

Cheers,
Daniel

-- 
Daniel-Constantin Mierla - http://www.asipto.com
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