Northern Virginia residents soon will have a chance to buy the Bell telephone equipment they're now leasing from the Chesapeake & Potomac Telephone Co., if state regulators approve.

The company wants to sell the standard, Trimline and Princess telephones customers already have in their homes as well as those styles of telephone equipment now in the C&P inventory. The sales proposal reflects marketing changes being made by the Bell System as a result of deregulation of the telephone industry.

Any customer who doesn't want to buy a telephone, however, will be able to continue leasing equipment from C&P, according to Web Chamberlin, a company representative.

C&P already has filed a petition in Maryland asking for permission to sell certain types of telephones to single-line residence and business customers. The Maryland prices, which take effect Jan. 13 unless disapproved by the Maryland Public Service Commission, range from $19.95 for a standard rotary desk or wall phone in place at the customer's premises to $54.95 for a Trimline Touch-Tone desk or wall phone in place at the customer's premises.

Equipment already in the customer's home but sold after a special 90-day introductory period, as well as telephones from the C&P inventory, would have higher prices, ranging from $34.95 to $74.95.

Chamberlin said the price proposals now being prepared for Virginia and the District of Columbia are similar to the one for Maryland.

"The prices in Virginia and D.C. may not be identical to those in Maryland, but they will be close," Chamberlin said.

He said the company will file price schedules for Virginia within the next two to three months. Whatever C&P proposes for Virginia must be approved by the State Corporation Commission. The Washington proposal must be authorized by the D.C. Public Service Commission.

Present plans call for C&P to provide a 30-day warranty for equipment already in place in a customer's home. The warranty would begin the day of purchase and would cover repair or replacement of the telephone.

The company would provide a 90-day warranty for equipment purchased from company inventory and would also cover repair or replacement.

After the warranty expired, the customer would be responsible for repair or replacement. C&P would continue to provide repair service, but at a fixed rate.

Customers who choose to buy equipment from C&P could pay cash, use a credit card or have the price included in their monthly telephone bill, Chamberlin said. The customer could be billed once for the total price or could have the amount divided into as many as four monthly payments. No interest would be charged on the extended payment plan.

The phone company may not be so accommodating, however, to customers who want to exchange old telephones for new equipment in order to take advantage of the C&P sale offer.

"We will take a hard look at what's being turned in," Chamberlin said.

"If you decide that your stuff doesn't look good and you want something new just in order to have new equipment in place when we begin to sell in-place equipment, we may not allow it," he said.

The company hasn't worked out exactly what restrictions will be imposed to keep customers from doing that, he said.

But C&P probably will permit customers who want to expand service by adding extension telephones to do so, he said. If a customer now has one main phone, for instance, and wants to install two extension phones so he can buy all three for $19.95 when the Bell sale begins, "we probably would allow it," Chamberlin said.

But the equipment would have to be in place on the first day of the special sale, he said.