[Spce-user] NGCP as Web2SIP gateway

[Alexey Rybalko]

Hi!

Present implementation of WebRTC is a headache if someone making the bridge
to a legacy SIP cloud. SRTP, SDP media-profiles...you know. Since the
version 2.3.0 of your ngcp-medaproxy-ng Sipwise feeds our hope to get a
relief completing that mission of service convergence :) Playing a couple
of days with SPCE with no valuable success. More questions appear.

The setup is:

1) sip:provider CE,
2) JsSIP as ref. implementation of SIP/WS-client
3) OverSIP as SIP proxy for websocket clients (SPCE comes without
websocket.so, but some reconfiguration is required either if this module
presents)
4) softphone (like X-Lite or Jitsi)

The first problem was that Kamailio registrar can't save "Path" header from
JsSIP REGISTER request. Extending DB field "kamilio.location.path" from 128
to 255 characters made that work :) Not sure this is a proper trick but it
works: JsSIP cant register and send INVITE to a "legacy" softphone. But
that's all. The  problems are:

1) SPCE (Kamailio) can't locate JsSIP to forward INVITE from softphone.
"Path" header support is enabled however. TCPdump shows us round-robin
traffic from 127.0.0.1 to 127.0.0.1. Softphone receives 408 (Request
timeout) from registrar. Should we use websocket.so instead of external
"websocket-able" SIP-proxy? What might be wrong here?

2) JsSIP drops outbound call (to softphone) on negotiation phase with 488
(Not Acceptable Here). No doubt that's because of unsupported SDES-SRTP and
RTP/SAVPF on remote endpoint. ngcp-mediaproxy is intended to solve this
issue:

*"..the complete SDP body is passed to mediaproxy-ng, rewritten and passed
back to Kamailio. Several additional features are available with this
protocol, such as ICE handling, SRTP bridging, etc."
*

Sounds good. However help is needed to move further. Any input would be
appreciated.


p.s. Is there some manual about packet processing inside mediaproxy-ng?

regards,
Alexey
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