If you've already got the phone you want, SIM-only deals tempt you with cheap rates for just the SIM card -- but your phone will have to be either unlocked or locked to O2 in order to use this option.
SIM-only deals start from £10 a month for a 12-month contract with 300 minutes and unlimited texts. The price for data is capped at a maximum £1 a day, or you can buy an add-on with unlimited data from £5 a month. If you have a BlackBerry, you'll need a BlackBerry bolt-on to get your push email -- that includes unlimited data and starts at £7.50 a month.
If you have an iPhone, and you want visual voicemail, you can pick up an iPhone plan from £15 a month. That's a 12-month contract that includes 300 minutes and unlimited texts, data and use of O2's Wi-Fi network. A tethering add-on means you'll pay no more than £2 a day to use your phone as a modem with your laptop.
If you do want a new phone, the cheapest contract is now a 24-month, £10-a-month bundle that includes 50 minutes and unlimited text messages. There's a decent selection of free phones on this deal, or if you're willing to shell out £50 you can pick up the very good.
Dongle users aren't left out, with new deals including a 30-day contract that cops you 1GB of data for a tenner.
The new O2 contracts are available starting today at the O2 Web site -- but it's still worth doing a spot of comparison shopping, especially since O2 has been struggling with data overload, thanks to the hungry iPhones that saturate its network in some areas. Try deal-comparison tools such as our own Mobile Deals section to make sure you're bagging the best deal for yourself.