I use a O2 pay as you go sim for work and top up £10 every 6 weeks. It is mostly incoming calls and I make a few calls now and then. I am after a iPhone so that I can use the sat nav on it, but was wondering what are my options as pay as you go, the O2 shop said I have to buy £15 credit a month and I get unlimited texts and web. I have to keep the same number. What's my options? Carry on getting top up when I need it and just see how much the web costs me? Anyone with any idea's?