I use dialup connection with my IPPhones which has a buildin modem without any issue on both codec G723 and G729. I sometime get better quality on the some phone if I use dialup then when I was braodband. this happens when I call most aftrican country where the termination is not good. This is because when I use broadband the media has to through some kinds of NAT transval while the dialup normally gets public IP so no NAT transval and the media gets the shorts path.
thanks
Mohamed
Jorge Crichigno <jcrichigno@conexion.com.py> wrote:
I think the data rates with overhead are as follow:
----------------------------------------------------------------
iLBC - 30 ms (a packet each 30 ms)
RTP payload: 50 bytes --> Rate: 13.3 Kbps
RTP: 62 bytes
UDP: 70 bytes
IP: 90 bytes --> total rate: 24 Kbps
-------------------------------------------------------------------
iLBC - 20 ms (a packet each 20 ms)
RTP payload: 38 bytes --> Rate: 15.2 Kbps
RTP: 50 bytes
UDP: 58 bytes
IP: 78 bytes --> total rate: 31.2 Kbps
-------------------------------------------------------------------
G.729 - 2 voice frame per packet
RTP payload: 20 bytes --> Rate: 8 Kbps
RTP: 32 bytes
UDP: 40 bytes
IP: 60 bytes --> Total rate: 24 Kbps
-------------------------------------------------------------------
G.729 - 4 voice frame per packet
RTP
payload: 40 bytes --> Rate: 8 Kbps
RTP: 52 bytes
UDP: 60 bytes
IP: 80 bytes --> Total rate: 16 Kbps
-------------------------------------------------------------------
G.711 - 20 ms (a packet each 20 ms)
RTP payload: 160 bytes --> Rate: 64 Kbps
RTP: 172 bytes
UDP: 180 bytes
IP: 200 bytes --> Total rate: 80 Kbps
El vie, 27-05-2005 a las 10:36, Iqbal escribi??:
> the 5.3, 6.3K are really theoretical, i dont think they include IP
> overheads, I used media_sessions.phtml, and looked at the actual calls
> per codec, and I dont think u can really get a good call without 50-70K,
> also most bandwidth providers (at least here in the UK) are
> asymmetrical, so even on a 128K, u could have problems.
>
> Having said that I have done a nice call on xlite using ilbc on dial up.
>
> Iqbal
>
> Kofi Obiri-Yeboah wrote:
>
> >Just to add a few more
details, Greger is right to point out the quality
> >inferiority of G.723 compared to those of G711 and G729. In fact, in most VOIP
> >deployments, in order to quarantee interoperability, a minimum bandwidth of
> >128K is specified. However to reach the wider "lower bandwidth areas" most
> >service providers are opting for G.723 which uses either 5.3 or 6.3K. At this
> >low bandwidth transmission needs, one could literally reach "dial up modem"
> >equipped areas. in fact most VOIP phone hardware and software are begining to
> >specify G.723 as their default codec. Note that until the direct media
> >connection phase of a VOIP vall setup, wide bandwidth is not required. Also
> >note that analogue phones have a maximim bandwidth need of 3K, hence even the
> >low quality of G.723/5.3K, compared to the average analogue phone call, is
> >superior
> >
> >
>
>
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