The phone number for T-Mobile customer service is 877-746-0909, as of 2015. Customers can dial 611 for customer service when calling from a T-Mobile phone. Hearing or speech-impaired customers can call 877-296-1018.

Customer representatives are available seven days a week from 3 a.m. 10 p.m. Pacific Time. Automated customer assistance is available 24 hours a day, seven days a week.

To activate a prepaid account card, customers can call 877-778-2107. To manage a prepaid card, customers can call 877-778-2106, and to refill a prepaid card, customers can call 877-720-5195. Assistance with prepaid cards is available from 4 a.m. to 11 p.m. Pacific Time.