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.

Many of the basic, budget plans from the big three carriers have lower prioritization and less features than some prepaid alternatives.

When it comes to finding a prepaid phone plan, traditional carriers like AT&T, Verizon and T-Mobile aren't your only options. Here are our picks for the best prepaid phone plans this holiday season.