Theo Markettos wrote:[color=blue]
> Let's say I want to set up my own dialin server. I don't have a spare PSTN
> phone connection. Getting a geographic incoming number is usually
> straightforward (Sipgate et al are free). What are the issues with trying
> to do this with VOIP? I suppose the problem is I don't actually want V near
> any IP. Is there any protocol to having the PSTN-VOIP gateway act as a
> modem, rather than a voice sampler? I know there are protocols for fax, but
> for modem data?
>
> Is there some way I could get, say, an encapsulated PPP stream over the net?
> Are there services that provide this?
>
> Thanks
> Theo[/color]

This is difficult to make work. What bitrate you can achieve will
depend on the quality of the IP link between you and your VoIP service
provider. I'd say to probably hope for around 14,400bps using g711a/u
codec. There is an ITU standard called V.150.1 which is the modem
equivalent of t.38 but I've never heard of any equipment or service
providers using it. Timing critical connections such as modem and faxes
are always going to be a pain over IP due to the lack of strict timing
between source and destination on a IP network.

If you are using a Linksys ATA then your best bet is to read this I
wrote a while ago about faxing over IP:

[url]http://www.provu.co.uk/pdf/sipura/ip_faxing_sipura_linksys.pdf[/url]

otherwise, try and apply the same settings to whatever ATA you have. It
basically involves turning off features such as variable jitter buffers
and echo cancellation which can all interfere with the modem comms.

Someone asked this very same question on here not so long ago I'm sure.
Try searching the list archives to see who it was and if they got
anywhere with it.

Another option would be to search for a dialup ISP who simply allow you
to connect as and when you want for no charge other than the phone call,
such companies exist... the name Geoisp springs to mind although I could
be imagining it.

cheers,
Paul.