It took nearly six years but T-Mobile has finally managed to add Apple’s (AAPL) iPhone to its smartphone lineup. Beginning on Friday, T-Mobile subscribers can preorder the iPhone 4, iPhone 4S or iPhone 5 on T-Mobile’s website. With the carrier’s new no-contract policy, the iPhone 5 starts at $579.99 for the 16GB model, which can be paid up front or as a $99 down payment plus 24 monthly installments of $20. The iPhone 4S can be had for $69.99 up front and 24 payments of $20 per month, and the iPhone 4 costs $14.99 up front plus $15 per month for 24 months. T-Mobile notes that the iPhone 4S and iPhone 4 are only available in select markets, while the iPhone 5 is available nationwide.