Three have 3 different types of plans. Talker plans offer a flexible allowance of units which can be used for minutes or texts (1 unit = 1 minute = 1 text) plus an internet allowance. Texter plans have a fixed allowance of minutes, 5000 texts plus an internet allowance. Three's One Plan offers 2000 minutes, 5000 texts, 5000 minutes to other Three mobile numbers and all-you-can-eat data. The all-you-can-eat data is available as an add-on on any of hte Talker and Texter plans for an extra £3. Where the iPhone is concerned 3 have Talker, Texter and One Plans available and there are different monthly costs for the same plan depending whether you choose the 3GS, the iPhone 4 or the 4S.