Now that is what could be extremely useful.

Key points from the page:

... signals are sent directly from one handset to another, without using the cellular network. And it uses the 900 MHz ISM band...

That is what we are after

...The effective range can be in excess of 6 miles, but the frequencies used are line-of-sight and are blocked by structures and vegetation. Practical ranges are usually 1 to 2 miles...

That is possibly due to their use of FHSS

...It uses FHSS technology on the 900 MHz ISM band as an unlicensed transmitter...

And FHSS may not be as good as some other strategies
for dealing with noise and distance.

Depending on the radio we could see better or worse,
but this is definitely what we should be able to do
with the hardware, if it is capable and if we could only find the APIs.

It is for certain in nokia-binaries that this is to be found,
but I am not kitted up to hack into that right now.