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.

“So what these hackers are doing is calling your cell phone providers over and over again, [and] requesting new SIM cards ... Verizon, T-Mobile, AT&T, all guilty,” she declares.

Citi and AT&T are offering holders of a new card the opportunity to buy a mobile phone and be reimbursed for the cost, targeting fans of both smartphones and online shopping. With the new AT&T ...