Once upon a time, a mobile phone contract was 12 months. Then it edged to 18 months, but more recently, 24 months have been the norm. If the 12-month period still appeals, you can always opt for Vodafone Red Hot, although it does come at a price.It's a nice idea though. Sign up for a 12-month deal, get the latest phone for a monthly fee, pay for the tariff, then return it after a year and do the same thing all over again. What could possibly be wrong with that?On the face of it, nothing at all. But you do obviously pay more - and you don't ever own the phone. So, for example, a Samsung Galaxy S III comes in at £47 per month with unlimited calls and 2GB of data, an iPhone 5 will cost you £59 for each of the 12 months and a Galaxy Note II is yours for a £52 monthly fee.But note that you do have to send it back, so if you damage your phone or lose it, you will have to pay a premium or indeed, the price of a replacement. So if you aren't the most careful of people, it might not be for you.On the flipside, if you are the kind of person who really needs to have the latest kit and doesn't really care about the hardware at the end of the deal, this might well work for you. More details at the Vodafone website.