If you want a localised, short range radio communication network for places where no telephone exists, you might consider using two-way radios or Citizen Band radios. Small handheld two-way radios have range limited to 1 or 2 miles but can be a solution when range is not an issue. CB radios are quite cheap to buy in the UK either new or second hand. Range varies depending on terrain (as they transmit line-of-sight) and antenna used but can be up to 10 miles. It's worth buying everything you need in the UK which would include radios, microphones, antennas, power supplies, cable and wiring. Car batteries, bought in the destination country, can be used as power supplies where mains electricity is not guaranteed. You will need a way of charging the battery either using a mains charger (when mains or generator electricity is available at least some of the time) or solar panels. It may be worth finding out if the UK frequencies will be allowed in your destination country and not conflict with any existing users of this frequency (contact the country's government telecommunications department).