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.
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 escribió:
> 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 fe
w 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
> >
> >
> <
BR>>
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