AT&T has a subsidiary called Centennial. Look at the AT&T Mobility plan which is in English for more information.

Note: If you are a Puerto Rican resident you may qualify for a double discount. This is in addition to the $9.25 standard federal discount. The Commonwealth of Puerto Rico will offer a Lifeline Customer an additional $3.50 discount. Centennial will discount the monthly phone bill you have by around $12.75

Website: www.att.com/plans/wireless