Mystery Caller has a habit of getting lost. He is after a GPS enabled phone to use with his existing prepay SIM. With a budget of £60-£80 he set about seeing what the networks had to offer

Mystery Caller has just started his first year at university. Money is tight so he is looking for the best mobile broadband prepay plan out there. What did the big providers have to offer?

Mystery Caller is off to Australia but doesn’t want to take his expensive smartphone. He has a budget of £80. Could the networks offer a cheap but effective prepay option?

Mystery Caller is spending too much. He tops up £40 a month, and is looking for a package that will make calling and browsing cheaper. A new phone wouldn’t go amiss neither.

After seeing his fi rst Christmas ad on the TV, Mystery Caller has decided to get his act together and start writing his present list early. But what will be the big selling phone this festive season for the networks?

Mystery Caller’s company is looking to consolidate its workers calls and data spend into one business tariff, with nearly 50 devices needed and a monthly clawback of £15-£20 by each employee

Mystery Caller has scored a promotion and been told by his boss he can have a £35 a month allowance to spend on a business phone. Would the networks get inventive, or will it be BlackBerry all the way?

Mystery Caller is after a new phone with a decent camera on a £25 a month contract, ideally with around 300 minutes, unlimited texts and some data allowance. What could the networks recommend?

It’s Mystery Caller’s grandad’s 75th birthday, and he needs a mobile that’s easy to use, read and understand. The budget’s pretty flexible too. What can the networks suggest?