We've built an awesome PAYG tariff comparison engine, and in doing so, we've had to make a few assumptions:

- you're a normal user - you use the phone when you need to, and don't wait for a certain time before making calls

- you don't know what network the people you phone are on

- you already use a mobile, and know your usage

- if you want data, you're likely to use it every day; we've picked the best value data add-on to help you compare deals