No Mobile Phone Signal

[UKSWF]

I am moving to an area (UK) where there is a very poor mobile phone signal outdoors is reasonable indoors is very patchy. It has been said to use the broadband WiFi. But i am a little confused. I use Apple iphone and can speak iphone to iphone no problems. I imagine I can speak via Skype to someone who has Skype but what about a general phone to say the vet for example? Am I missing something or is there another solution. I am currently with O2 mobile.
Thank you.

[Fitzer]

O2 (and others) offer WiFi calling so if you have that enabled on your phone (under mobile data in settings) when your mobile signal is too weak to make a call it should allow you to make and receive calls as normal but the call is routed via your broadband..

[ubasses]

We have the same problem in our small village, and use a booster, whch is provided by vodofone for free. With that we get full signal on our phones, might be worth you asking O2 if they do anything similar.