More than 300,000 Hoosiers registered for the Do Not Call list in February and the next registration deadline is May 16.
The Do Not Call list is a telephone privacy campaign that protects residents from potential phone scams.
Those who register may still receive random calls from unknown numbers and Indiana Attorney General Curtis Hill encourages people to ignore those calls.
Indiana residents who wish to sign up can call 888-834-9969 or visit indianaconsumer.com.
People can register the Do Not Call list at any time, but the updated lists only become available to telemarketers in three-month increments.
The attorney general’s office said Hoosiers who register by the May 16 deadline will begin receiving fewer telemarketing phone calls starting July 1.