Could there be a device that gives give off a home network signal that
> your cell phone can connect to as it does your service provider? You
> could then user your cell handset for VOIP calls when near such a > device.
Technically? I suppose so, although the device would have to spoof your phone's preferred carrier to get the phone to connect. But in practice, there's no way this would happen since the frequencies in question are licensed to the cell carriers, and they would not be at all amused at freelance low-power competition that would steal their calls.
There is talk of special wi-fi enabled phones doing this, but this
> could be used with any phone, and could possibly be wi-fi enabled as > well.
WiFi is different, since it uses the same unlicenced band as 2.4MHz cordless phones. For that matter, why screw around with WiFi? Just make it a cell/cordless phone.
R's,
John