(a) The commission may from time to time determine and prescribe by order changes in the form of the schedules referred to in this article as it finds expedient, and may modify the requirements of any of its orders or rules in respect to any matter referred to in this article.
(b) If the rates for any commercial mobile radio service are not subject to regulation by the commission as a result of federal law, then the commission may exempt the service from any tariff-filing requirement.