(a) The monthly rate for tel-assistance service shall be set initially by the commission at the lower of: (1) The lowest priced service available to the consumer at the time of his or her application; or (2) $7.50. All usage exceeding $2 in value shall be charged for at the otherwise applicable tariff rate. No other local voice telephone service may be provided to the dwelling place of a tel-assistance consumer, nor may individual line foreign zone or foreign exchange service be provided to a tel-assistance consumer. An eligible telecommunications carrier may not impose an order processing charge or line charge when an existing consumer who is eligible for tel-assistance service changes to such service, nor may any charge be made when a tel-assistance service consumer loses his or her eligibility and changes to another class of residential service: Provided, That charges for the initial installation of service for a new consumer, or charges for moving a consumer's service from one dwelling place to another shall be made at the otherwise applicable tariff rate.
(b) The commission may, upon having set the rate initially for tel-assistance service as herein provided, change such rate from time to time upon a finding that is reasonable to do so, and may, in connection therewith increase or decrease the amount of local service usage provided as a part thereof.