(1) Each carrier, billing aggregator, and service provider must have at least one business office to provide customers and others with access to personnel who can provide information on services and rates, accept and process service applications, explain customers' bills, adjust errors, and generally represent the entity. If one business office serves several exchanges or states, toll-free calling to that office must be provided and the office must be staffed during Montana business hours.

(2) Local exchange carriers which provide billing services for other carriers, billing aggregators, or service providers shall include in such bills the toll-free telephone numbers of such carriers or service providers or alternatively, the toll-free numbers of their billing aggregators, which are provided to the local exchange carriers in accordance with (3) .

(3) Carriers, billing aggregators, or service providers which bill through local exchange carriers are required to provide the toll-free telephone numbers required in (1) to all such local exchange carriers.

(4) Local exchange carriers and billing aggregators must provide a carrier's or service provider's toll-free number to a customer, upon request, at no charge, for any entity for which it bills.