"Gordon Henderson" <gordon+usenet@drogon.net> wrote in message
news:fqrjpj$1qjv$1@energise.enta.net...
> In article <8qSdnbgXqYPCtEzanZ2dneKdnZydnZ2d@bt.com>,
> R. Mark Clayton <nospamclayton@btinternet.com> wrote:
>>
>>"Michael" <kj@nvb.com> wrote in message
>>news:3Rfzj.61968$os2.5833@newsfe3-win.ntli.net...
>>> Folks
>>>
>>> I run a voip line on the end of a cable connection from Virgin, and I
>>> fully understand that the system works as the cable is 'always on'.
>>>


>>It is possible to VOIP over an ISDN connection, but I never tried it. The
>>quality would probably be similar to PSTN, but not as good as raw ISDN.
>>
>>It was possible to VOIP over dial up, but as you can imagine the quality
>>would be poor.
>
> I've managed to have a successfull VoIP conversation over a shakey 33.6K
> modem connection using the GSM codec. I imagine it might have been a
> shade better using g729... Latency was a bit high (as ping times are
> over dialup), but other than that it was "usable"...
>
> If you can get both channels of the ISDN line up, then running a full
> bandwidth codec (g711) over it via SIP or IAX should't be an issue at
> all. Bit of a waste of the lines though, but if you had free Internet
> connectivity over it, it might be better than paying BT ...

If you can get both lines up it should be a lot better - radio companies
used (possibly still do) to have a way of connecting over both channels of
basic rate with a better algorithm to give mid-fi mono voice.

>
>>Perhaps someone can tell us if you can VOIP over 3G and how many channels
>>you need, bear in mind though that the network providers will
>>intentionally
>>impede this working easily.
>
> I've had a colleague call me via VoIP and a 3G connection. Bit laggy,
> but otherwise OK. Not had a chance to try myself yet. Maybe this weekend
> I'll have a play...

Good luck.

>
> Gordon