VOIP with Vodem?

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johnr

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#57100 6-Jan-2007 16:19

cokemaster: As far as I know switching into HSPDA mode is done automatically by the network. There doesn't appear to be any settings that one can tweak to 'force' it onto HSPDA.

You'll notice that while its in '3G' mode rather than HSPDA mode that latency tends to be a bit higher as well...

Cokemaster is correct

sbiddle

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#57112 6-Jan-2007 17:31

Oyajipunk:

I don't understand why a PC to PC call should be better quality than PC to phone though (mentioned by Paradoxsm). Is that much quality lost just by passing through a telephone exchange and telephone wires? I would have thought most of the sound quality and delay problems would be caused by the conversion of sound from analog to digital, and the 'latency' in the network. Both of these factors would surely be the same for a PC to PC call as for a PC to phone call? I'll try a PC to PC call later and let you know the results.

You've just answered you question yourself. You say you don't understand why a PC to PC call should be better than PC -> PSTN. You then mention the "conversion of sound from analog to digital".. This is part of the problem - for a VoIP to PSTN call somewhere along the line the call has to be connected to the PSTN network. As Juha has mentioned this doesn't happen anywhere in NZ so you've got the high latency of 3G to an overseas gateway (at minimum 300ms and possibly up to 400ms), the conversion to PSTN, the possible conversion to a VoIP circuit for it's trip to NZ and then conversion back before the local PSTN number if Auckland rings. That's means your phone call is taking the long trip!

Many people have said SkypeOut calls to NZ landlines are pretty average at the best of times so it's not necessarily just a VoIP problem. Personally I hate Skype since it's a proprietory format and uses *your* bandwidth for their P2P network but the reality is the abundance of standalone Skype phones now that don't require a PC has the potential to finally deliver Skype to the masses and create a power to be reckoned with.

Oyajipunk

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#57142 7-Jan-2007 09:01

juha:

Did you mean to say you were on GPRS and not UMTS, or that you were on UMTS but not HSDPA?

Sorry, no idea. I am only going by what was written in the Vodem instructions, and all they mention is 3G Broadband and 3G.

I'll try a call to the UK as well and see if it is much different, but I only suspect it will be a marginal difference.

Thanks again.

juha

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#57143 7-Jan-2007 09:36

Cellular technology acronyms are notoriously silly - check out GSM for instance - and hard to memorise so I'm not surprised Vodafone tries to "hide" them. I believe that "3G" is UMTS, or the first-generation fast-ish cellular broadband introduced by Vodafone and other GSM operators. Runs at 384kbit/s down, 128kbit/s up and has latency of 220ms+. "3G Broadband" should then be the HSDPA upgrade to UMTS, that currently gives you around 1.1Mbit/s+ down, and 2-300Kbit/s up, with 130ms latency (although as sbiddle has shown, if you pick the right APN, you get 90ms instead).

In HSDPA mode, VoIP should work... in theory at least.

Juha

Oyajipunk

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#57149 7-Jan-2007 12:09

FINAL RESULT: IT WORKS!

I just called a landline in the UK with Skype on my Mac 12" Powerbook, and the line quality and delay was totally acceptable. No echoing at all. Sound quality a bit muffled but totally audible. Small amount of delay, meaning you had to wait until the other person had finished before you started speaking, but not any worse than some landlines I have used in the past.

The "3G Broadband" (highest speed) lamp was illuminated on the Vodem the whole time.

If PC to phone worked, I know PC to PC will work, so that's next. Now all I have to do is monitor how much of my 1G data cap these calls are using.

All in all, a very sucessful Sunday!

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