Except as provided in subsection (b) of this section, a person that operates a one–call system in the State shall register with and obtain certification to operate from the Commission. A person operating a one–call system on or before July 1, 1990, is automatically registered with and certified by the Commission to continue to operate. The operator of a one–call system shall install and make available an underground facilities information exchange system in its one–call system in the State. The underground facilities information exchange system shall be available to any caller at all times. The Commission may grant, amend, or revoke the certification of a person operating a one–call system.