The attack occurred between Oct. 6 and Oct. 10 and affected 250 Verizon prepaid customers.

“We recently identified possible unauthorized activity involving about 250 prepaid wireless accounts.

Account access also potentially enabled attackers to process unauthorized SIM card changes on prepaid lines.

Additionally, Verizon reset the Account Security Code (PIN) of affected customers.

Verizon also encouraged customers to create a new PIN code and set a new password and security question.