T-Mobile hopes you don’t need to return your phone or a newly purchased service line, however, they understand these things can happen.
Did you purchase your device in the T-Mobile store or an authorized third party dealer? If so, the return or exchange must be done within a max of 14 days after the device was purchased or leased. Some customers will be charged a restocking fee depending on if the device was received after the specified time length. If the phone was purchased from an authorized dealer, the device must be returned to them in order to receive the full refund.
Online or phone purchases must be returned or exchanged within 20 calendar days of the date you placed your order.
If you have returned a T-Mobile device and are in the market for a new phone, follow this link and compare the hottest new phones.