Hello All,
I am running an IP telephony application on a cellphone. The application
uses the pjsip stack. I find that when i place a call using this cellphone
application, the call goes through but voice is one sided. The cellphone
running the app cannot hear anything.
When i look at the log on the cellphone, i see the following error
"RTP decode error: Unknown pjmedia error 220122"
I looked at the source code and found that in file rtp.c, there is a check
for version number in the RTP header.
/* Check RTP header sanity. */
if ((*hdr)->v != RTP_VERSION) {
return PJMEDIA_RTP_EINVER;
}
and RTP_VERSION is defined as 2.
Using wireshark, i have captured RTP packets destined to the cellphone and
upon examining the RTP header i see that the version number is indeed 2.
What else could be causing this error ? Is there any other check which
would produce this error output upon failure ?
I have attached a file showing my wireshark capture.
Thanks and Regards,
Vikram.
PS : I briefly outline the system setup
Cellphone uses Wi-Fi to hookup to the internet with IP 192.168.1.101.
Router is connected to a modem through a series of switches. The cellphone
is behind a double NAT. Cellphone app, tries to register with Asterisk
through an outbound proxy server(Kamailio + rtpproxy). The proxy server
rewrites SDP to force rtp through an rtpproxy. Both Asterisk and and the
outbound proxy have Public IP addresses.
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