(a) Required charging method.--In addition to any other method of charging offered on an optional basis, a telecommunications utility providing local exchange telephone service to residential customers within a certified exchange area must provide service which charges, for calls originating and terminating within the same local calling area, on the basis of a flat monthly fee for all such calls made.
(b) Options.--If the commission determines that a telecommunications utility may offer to residential customers an optional method of charging for calls originating and terminating within the same local calling area based, in whole or in part, on the duration or distance of the call, it shall also offer a rate which charges for such calls only on the basis of the number of calls made.
(c) Rate relationship.--In addition to any other requirements imposed by this title, the rates for services required or permitted pursuant to subsections (a) and (b) shall be maintained at just and reasonable levels in comparison to one another.
(d) Nonresidential rates pursuant to another section.--Nothing in this section shall preclude the commission from establishing rates for other classes of telephone service based upon another section of this title.