(See screen shot in post 3) OK this helped me so it might help others. Taking Column 1 as an example. If you go for the 100m 100texts deal you will pay a lot for the handset less per month. if you get the 64G version you will end up paying £15.12 pm (.15 per minute) for your airtime one you take out the cost of the phone. On their sim only solo monthly contracts (which you can't get for an iphone by the way but is just put in the table for comparision purposes) the same number of minutes and texts will cost you £10.21 pm. Where as Column3 the 600m 500t deal with the same handset you will end up with £18.33 pm month on airtime which compares well with their solo deal (£20.42pm) The sweet spot for T-mobile contracts is probably the 900m 500t package where you get down to 2p a minutes call charges. The other conclusions I come to: 1) Buying unlocked from the Apple store and getting sim only (T mobile don't do such a sim but other uk carriers do) can be cheaper is you are careful to calculate the true costs. 2) If you are in contract now it is sensible to buy an unlocked and stick your existing sim in. It is going to be more expensive to cancel and start afresh. 3) We are moving to a point where the only advantage I can see to a contract phone is spreading the cost. You don't get you handset subsidised you just end up paying the same amount over 2 years - which I grant you is good if you don't have the cash up front.