The following telephones shall be exempt from the requirements of Section 13-706 of this Act: telephones used with public mobile services; telephones used with private radio services; and cordless telephones. The exemption provided in this Section shall not apply with respect to cordless telephones manufactured or imported more than 3 years after September 19, 1988. The Commission shall periodically assess the appropriateness of continuing in effect the exemptions provided herein for public mobile service and private radio service telephones and report their findings to the General Assembly.