information and Communication Technologies [No. 15 of 2009 135 provisions of this Act, the terms and conditions of the licence, the guidelines issued by the Authority or any other relevant law. 20. (1) The Authority may, by declaration— exempt a person or class of persons, for a limited or unlimited period of time, from the requirement to hold an individual licence or a class licence under this Part; or Exemption of specific persons, activities, etc. specify activities for which an electronic communications licence shall not be required. The Authority may, where it issues a declaration under subsection (1), reverse its decision if the licencing of an exempt person or class of persons, or exempt activities, becomes necessary for the purposes of this Act. The Authority shall, where it reverses its decision under subsection (2), notify in the prescribed manner and form, the affected persons, and give the reasons for the reversal before effecting the reversal. 21. Nothing in this Act shall be construed as exempting any person undertaking an activity that is exempt from any licencing requirements under this Act from complying with the other provisions and requirements of this Act. Obligations of persons undertaking exempt activities The Minister may, by statutory instrument, declare certain services as reserved services where the Minister considers it necessary to do so, having regard to the strategic and policy considerations related to providing the service. Reserved services (1) A holder of an individual licence shall provide the following essential electronic communications services twenty four hours a day, seven days a week, at the prescribed level of quality, without discrimination: Provision of essential services emergency service with priority routing, to enable a member of the public to make contact with the police, the tire brigade and the ambulance service; directory assistance service, to enable a subscriber to obtain a telephone number through the assistance of an operator or through automated means; (c) operator assistance service, to enable a subscriber to obtain assistance, including accessing services, setting up calls, remedying faults and directory services; and