(a) An incumbent local exchange company with one million or more access lines shall file tariffs, and the commission shall determine reasonable rates to be charged by the company for:
(1) call forwarding;
(2) direct inward dialing; and
(3) any other mechanism the commission determines should be used as an interim telecommunications number portability measure by a new entrant.
(b) An incumbent local exchange company with fewer than one million access lines that serves an area in which a certificate of operating authority or a service provider certificate of operating authority has been granted shall, not later than the 60th day after the date of a bona fide request, file tariffs in accordance with Subsection (a).

(c) Not later than the 60th day after the date a company files tariffs under Subsection (b), the commission shall determine reasonable rates in accordance with Subsection (a).