(a) Residential telephone subscribers may enroll on the Tennessee Do Not Call Register in the manner prescribed by the authority. Enrollment shall take effect thirty (30) days following the first day of the succeeding month of enrollment by the subscriber.

(b) State government telephone subscribers may enroll on the Tennessee Do Not Call Register in a manner prescribed by the authority; provided that only the administrative head, or such person's designee, for each state department, agency, board, commission and other entity of the state, including the legislative branch and the judicial branch, may designate telephone numbers for such department, agency, board, commission or other entity of the state to be enrolled on the register. Enrollment shall take effect thirty (30) days following the first succeeding month of enrollment.