Dmitry- > Jeff, do you mean that operator may impair packets on edge and leave > intact switching to umts? Yes if the data packets are RTP packets (and possibly SIP, I've heard from some customers lately that a few carriers are using more sophisticated blocking algorithms). But again, only some carriers might do it. You could be having some other problem. This is why I suggest Wiresharking so you can post debug samples of what you're seeing -- maybe some packets out of sequence, maybe some missing, etc. It's hard to guess on something like this. -Jeff > On 5/10/10, Jeff Brower <jbrower at signalogic.com> wrote: >> 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. >> >> > > -- > Sent from my mobile device >