See inline.

I need help to understand ser+rtpproxy.

How may I configure rtpproxy options to run with ser/nathelper on the same box ?

rttproxy options : usage: rtpproxy [-2fv] [-l addr1[/addr2]] [-6 addr1[/addr2]] [-s path] [-t tos] [-r rdir [-S sdir]]

Just start rtpproxy without options and it will listen on the standard socket compiled into rtpproxy and nathelper.so.

SER communicated with RTPPROXY via unix socket. Does RTPPROXY rewrite INVITE/REGISTER message with info from SER?

Yes, when you call the appropriate functions. Read the Getting Started document (chapter 1 + the rtpproxy example chapter) to get detailed info.

private-------FW+NAT------SER+RTPPROXY------ public network network

which ports must be opened on FW box for INVITE and/or REGISTER methods are they the same than on rtpproxy ?

If you have a firewall that denies all outgoing ports except those explicitly opened (most home routers/FW allow outgoing): SIP messages: udp (and TCP if you use that) port 5060 RTP: udp 35000-65000 (can be changed in rtpproxy's rttp_defines.h) Both to your SER+RTPPROXY server.

g-)

g-)