Chesapeake & Potomac Telephone Co. yesterday proposed new rates for connecting customer-owned telephone equipment, as required by a Federal Communications Commission order upheld recently by the Supreme Court.

Under the proposed new rates, however, residential customers would have to wait a long time before achieveing economic benefits from buying their own equipment and having the devices hooked up to the national telephone system.

The rates were filed yesterday by C&P with the public and West Virginia and with Virginia's State Corporation Commission. A similar petition will be fled next week in Maryland, said C&P spokesman R.W. chamberlin.

Washington-based C&P is a wholly owned subsidiary of American Telephone & Telegraph Co., the giant national utility which joined other telephone firms in fighting the FCC order all the way to the Supreme Court.

AT&T chairman John D. deButts has vowed that his company will do all it can to comply with the FCC order, but has warned of damage to the quality of telephone service from attaching non-company equipment to the national network.

The C&-P proposals filed yesterday include some differences in charges for the various jursidition but in general provide for a small monthly reduction in rates when a customer supplies a baic or extension telephone, and specific charges for connecting equipment under the plan.

In addition, C&-P has proposed what amount to rate reductions for consumers with one or two touch-tone telephones, presumably to make the AT&-T equipment more competitive with non-Bell Systems products.

Using the District as an escapmle, C&-P has proposed:

A credit of 70 cents a month per telephone (in effect a rate reduction of that amount) for customers who supply their own devices. C&-P said in its petition that the 70 cents represents that part of monthly bills allocated to the telephone instrument which customers normally have rented from local telephone companies in the past.

Separate charges for touch-tone services and for access lines capable of hadling touch-tone calls. The line will cost $1.02 a month for customers with Bell System or their own touch-tone telephone from C&-P or no charge if the device is owned by the coustomer, C&-P now charges $2.02 a month extra for a touch-tone.

A new structure of service connection charges, so customers with their own devices will not be charged for sets they connect themselves. The proposed charge for connecting new service will be $15.40 if a visit is required to the house or office and $9.00 without a visit.

The FCC order requires that a jack supplied by the telephone company be used to connect privately owned devices. C&-P has proposed charges of $2.20 to install a jack and $5.95 for wiring each telephone location.

Yesterday's proposal means that a customer with basic D.C service costing $9.99 a month would save 70 cents a month by purchasing a telephone. But there would be additional onetime charges, such as jack installation.

On the open market, basic black telehpones may be purchased for less than $30. That means it would take more than 40 months for a customer to recover the initial investment in a telephone alone, C&-P also has entered the telephone retail business at its phone stores, but the cheapest model currently is $39.95.

Non-Bell System equipment manufacturers do not expect many residential customers with one unit to buy their own telephone; where they may be succesful in competing with AT&-T is supplying extension telephones and equipment for industry and goverment.

C&-P's Chamberlin predicted yesterday that his firm will lose revenues and experience higher costs under the FCC order. Customers who elect to attach their own equipment must notify the telephone firm, and manufacturers must register all equipment with the FCC. By Charles Del Vecchio - The Washington Post