US WEST customers in seven states affected by a proposed class-action suit settlement will have to wait until late March to learn whether they will be receiving credits on their 1991 billings.

The suit involves US WEST's imposition of an inside-wiring maintenance fee on billings between March 1, 1982 and Dec. 31, 1989.The class-action suit was brought in federal district courts in New Mexico and Colorado after the Federal Communications Commission ruled that inside-wiring maintenance services are subject to outside competition and should not be included in US WEST customer rate structures.

Since that ruling, US WEST has contacted all affected customers giving them the option to remain with US WEST or seek other alternatives.

Customers in Utah, Colorado, New Mexico, Arizona, Idaho, Wyoming and Montana will be affected by the settlement if it is approved by the federal judges hearing the case.

The proposed settlement is scheduled to be presented in concurrent hearings in Denver and Santa Fe on March 18.

Customers who paid for the service during the affected period and who did not make use of the service will be eligible to receive 65 percent of the amount paid in the form of a refund. US WEST will have 24-months in which to make the repayment which could come in the form of a one-time credit or could be spread in smaller increments over the repayment period.

The settlement requires that the refund come from shareholder earnings and forbids the company from recouping any of the money in future rate hearings as a cost of doing business.

The service fee for Utah customers was about 65-cents per month and totaled about $60.45 during the affected time period. A 65 percent refund would net $39.29 on that amount. Customers who used the service prior to Dec. 31, 1989, are not eligible for a refund.

The total amount to be refunded will depend on the number of claims received once the settlement is approved. Officials say it is impossible to determine the total amount involved at this time.

US WEST spokeswoman Laura Scholl said the inside-wiring maintenance service remains available but is no longer included in the customer rate structure. It is an optional service that a customer must contract for separately from basic telephone service.