T-Mobile US and AT&T will each sell the iPhone 5S and 5C under installment plans as the industry moves to provide consumers with more flexible arrangements to pay for handsets. Pre-orders on the phones began today. On the lower-end 5C, both carriers will charge monthly payments of $22 while requiring no down payments on the $99 phone. For the $199 5S, T-Mobile will charge a $99 upfront fee and $22.71 a month, while AT&T will require no initial payment and $27 a month for 20 months. T-Mobile will, however, offer service plans for less money than AT&T under its new no-contract policy. Wal-Mart will offer the 5C for $79 and the 5S for $189 with a contract.