VOIP via Mobile Phone Data Connection

[Higgers]

Has anyone here ever tried making a VOIP call using a mobile phone as the connection to the internet? I'm curious to know if the internet connection on a mobile phone provides good enough latency for the above to be feasible.

[Exception OE]

I belive you can get Skype for Windows Smartphones. Can't say I've ever tried using it though.

[dejongj]

I know it is not the question...But considering that GPRS/3G data access is much, much more expensive then normal voice minutes on a mobile I have never bothered trying....But if my normal Vodafone 406kb data connection is anything to go by, I wouldn't even try it....There may be better providers but the latency is huge...

[Higgers]

Originally Posted by dejongj

I know it is not the question...But considering that GPRS/3G data access is much, much more expensive then normal voice minutes on a mobile I have never bothered trying....But if my normal Vodafone 406kb data connection is anything to go by, I wouldn't even try it....There may be better providers but the latency is huge...

I'm on Orange and I get 4Mb data per month for £3. How much bandwidth does VOIP use? It must depend on the codec used but I'll assume that an average bitrate is 9.6Kbps.

(I'm sure I read that a mobile phone call sends voice data at 9.6kbps using GSM.)

8 * 1024 * 1024 * 4 = 16777216 bits in 4Mb
16777216b / 9600bps = 1748 seconds
1748s / 60s = 29 minutes

So, the theoretical maximum (ignoring any overheads) talk time you can get out of 4MB at 9.6Kbps is 29 minutes in one direction. 300p/29minutes = 10ppm, not exactly brilliant. That also assumes that all calls are made to destinations that incur no charges from your VOIP provider. If you plan on having a fairly normail type of conversation in which both parties spend an equal amount of time talking then the talk time must be divided by two.

A few months ago Orange were promoting their 3G service and were offering 1GB of bandwidth per month for free. The above calculation for 1GB is:

8 * 1024 * 1024 * 1024 = 8589934592 bits in 1GB
8589934592b / 9600bps = 894784 seconds
894784s / 60s = 14913 minutes = 248 hours = 10.35 days

Not too shabby. If my maths are correct. Until the 1GB per month promotion runs out anyway.

Can someone who knows more about VOIP than me (probably all of you) comment on the above figures please? :-)

[Higgers]

Having just looked at the FAQ on sipgate.co.uk it seems I was at least a factor of four too optimistic with my calculations.

[dejongj]

You may want to check this out as well http://www.voip-info.org/wiki-Bandwidth+consumption in order to get a better understanding about the calculations.....

Remember that the needs are higher when you want full duplex communications.....Of-course you don't communicate constantly so it is not really twice as much....

[Monty Burns]

Originally Posted by Exception OE

I belive you can get Skype for Windows Smartphones. Can't say I've ever tried using it though.

Sadly it does not support voice yet ... but they say they "are working on it". Oh and I believe its being designed to work over WiFi as well rather than GPRS/3g but I guess this should not be too much of a problem to change on the phone.

[mucca_D]

http://www.theregister.co.uk/2005/08...nado_surfaces/

Looks like a voip application is being desinged for this phone and it will be able to route the call either by the mobile network or a wifi network.

Will be interesting to see if Orange UK adopt the new phone with the wifi unit for the UK market

D

[Higgers]

Originally Posted by dejongj

Of-course you don't communicate constantly so it is not really twice as much....

Unless you're my mother-in-law...

[dejongj]

That is good, very good...Reminds me of the Apprentice last Wednesday the poor Andy bloke just couldn't get a word in...So I think we can even state...

Unless you're female...