Voice over GPRS?

Terrence Barr - Evangelist, Java Mobile & Embedded Terrence.Barr at Sun.COM
Fri Feb 2 17:52:55 CET 2007

VoIP calls typically require approx. 120 kbit/s *each*
direction, that's 240 kbit/s for a two-way conversation.

UMTS gives you 384 kbit/s if you're lucky. Most of the time
it's more like 150 kbit/s, so VoIP will only work with
very poor quality.

Also, most data plans specifically prohibit VoIP usage
and may even prevent it technically.

VoIP over cellular is just not feasible at this point.

The pre-paid data is interesting, though, from a competitive

-- Terrence

ROB wrote:
> Bit rate=sampling rate x bit depth
> 1kb/s isn't going to get you too much audio.  Try encoding an mp3 at
> 1kb/s to see how audible that would be.  I think you'd be looking at
> something more along the lines of 32-64kb/s to get anything that you
> could understand.  It might be easier to make a phone call.
> Conveniently enough, I think the device will have that capacity as
> well.
> On 2/2/07, Robert Michel <openmoko at robertmichel.de> wrote:
>> Salve!
>> Does anybody has experiances/ideas about Voice over GPRS?
>> How long is the delay? It could maybe used for asyncron
>> voice communication Talk2Talk (instead of pushing a button)
>> In Germany did three Prepaid Provider published new Tariffs
>> with 0.24Euro/MB.
>> German pages:
>> http://teltarif.de/arch/2007/kw05/s24754.html
>> data cost calculator:
>> http://teltarif.de/mobilfunk/datenrechner.html
>> I think with this tariffs using mobil data becomes
>> interesting ;)
>> By using 1KB/s for audio and some overhead, let
>> us say 2 KB/s 0.24Euro/MB = 24 Cent for 500 seconds,
>> 60 seconds makes then about 3 cents. When both using
>> this 6 cents. Hmm that would be interesting when
>> the user makes often make brakes/pause in their talk.
>> Greetins,
>> rob
>> _______________________________________________
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>> community at lists.openmoko.org
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