ByMartin Lewis, Martin Lewis
Millions of people bought iPhones from o2 when it launched a few years ago, and many of those phones are now out of contract.
Yet you could still be paying a hefty £30-£45 per month tariff. But there is a simple way to slash this.
Sign up to another year's contract, still with o2, and for £15 a month you get 300 any time, any network minutes plus unlimited texts and data - the same you would pay £35 per month for if you simply carried on with an old contract.
Technically this is a 'SIM only deal' but forget that; you don't need a new SIM, just call up and ask to be transferred to the SIMplicity package and it happens instantly.
Alternatively if you are planning on upgrading or ditching your iPhone you can sell it at speed for around £200.
You could sell your iPhone for around £200
To find the best price for your old one use my comparison site www.mobilevaluer.com.