Dmitry-
> As far as I could understand, I was able to configure and
> compile symbian_ua_gui with TLS, VAS and G729 protocol to work with local
> Kamailio based server, all communications go through media-proxy, SRTP (on
> the same local server).
>
> In 3G mobile networks, everything works just fine and quality is superb.
>
> Now what I see when connecting two entities (Nokia E51) WHEN CONNECTED
> THROUGH EDGE (the place where both entities were located has *no* 3G access
> and this was simulated by switching the phones) there is a very bad quality
> of audio.
>
> Either the packets are too big for such a slow connection (you can mostly
> here about a half of each packet then overlapped by the next one) or my
> configuration lacks some other vital parameters. It is not like the behavior
> we hear in GSM connection ("robotizing", "bubbling") - just packets are
> overlapped.
>
> In general, the main problem with mobile networking is that you have a
> rather wide Inbound channel and very narrow Outbound channel.
And the other main problem is that many carriers block (or impair) voice transport over non-voice channels. In that
case you have to encrypt or otherwise "hide" RTP (and sometimes SIP) packets on data channels. Also when you say you
can "hear a packet" that's impossible because you're talking about 10 or 20 msec length of time -- less than 1/50th of
a second.
My suggestion would be to put Wireshark on either side of Kamailio and find out what is actually happening to your
packets. If it's a deliberate impairment you should be able to tell.
-Jeff
> Thus, if at
> least one entity has wide narrowband (3G, WiFi connected), the other side
> have clean incoming audio. The tests of the mobile network are the
> following:
> 1st entity: 0,22Mbps incoming, 0,07Mbps outgoing.
> 2nd entity: 0,15Mbps incoming, 0,02Mbps outgoing.
>
> According to at least this table (
> http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a0080094ae2.shtml)
> the link has enough bandwidth to serve one connection. Even 9Kbps each
> direction should be enough.
>
> The questions are:
> 1. Whether anyone tested symbian_ua_gui or symbian_ua in EDGE phone mode,
> not 3G or WiFi?
> 2. What could I check in configuration of pjmedia, pjsip in general and
> symbian_ua/_gui in particular to make it work on EDGE?
>
> Thanks in advance,
> Dmitry.
