8 Dec
2016
8 Dec
'16
12:02 p.m.
On 08 Dec 2016, at 11:29, Kristian Martens
<kristian.martens(a)ng4t.com> wrote:
Hello,
Hi!
I got a mobile to mobile call working for signalling
only. Two RTP
channels are being established successfully. But there are only a few
pattern sent over these channels (1 byte 0x23 as UDP payload). Is there
a setting I am missing in the configuration files? Please find attached
a .zip file with pcap and cfg files.
I didn't look at the trace yet but have you seen my comment about the
SDP file?
[0;m<000b> mgcp_protocol.c:830 Got media info via SDP: port 5502, payload 112
(GSM), duration 20, addr 192.168.17.100
[0;m<000b> mgcp_transcode.c:170 Checking transcoding: GSM (3) -> GSM (112)
Why would one use a dynamic payload type for GSM FR1? I am not sure if
the mgcp_mgw is optimized to avoid doing transcoding if input and output
codec are the same but use different payload types. I would think it is.
The 0x23 UDP payload is to establish a NAT state to be able to send
traffic (e.g. ringtone) to a call for a BSC behind a NAT (all traffic will
go from network->NAT/Firewall->MGCP MGW) and the only way to know the
port is to have the BSC send some data.
So in your trace I don't see:
* UDP traffic from BTS to bsc_mgcp_mgw
* UDP traffic from bsc_mgcp_mgw to 192.168.17.100:5500
* UDP traffic from 192.168.17.100:5500 to ...
you get the point. Maybe start looking for where the BTS is sending the
traffic to and take it from there?
holger