You can activate your AT&T SIM in-store, online, or by contacting customer service. The process is similar for postpaid and AT&T prepaid customers.

Prepaid phone cards are prevalent in immigrant communities ... A few of the larger phone card companies, such as AT&T and IDT, had websites where we could look up calling rates.

AT&T Prepaid is giving away free and discounted phones for tax season. Visit any store before April 17 to grab these deals.

Officials at Wal-Mart could not be reached for comment. Having entered the prepaid phone-card market just two years ago, AT&T is a late comer to the $2 billion calling-card market. Sources say the ...