I totally get that. Reception so poor in our house. I know this can't help you but might help others: Vodafone do a 'SureSignal' box. I think it obtains a Vodafone signal via the router. Now we all have 5 bar signal in every room of the house. It's fantastic. £50 off flea bay. Only works when you register each phone number.No idea why I bothered, reception is crap at home on BT.
Only have it because Mrs KE and I can iMessage each other for nothing wherever we are in the world.
Whatsapp is even better than iMessage. Totally free and can send pictures, video clips (also free) in a few seconds.