Satellite Business Systems, the McLean business communications firm, has filed formal applications to provide long distance telephone service, signaling clearly the partnership's intention to compete aggressively in conventional telephone markets.

The filing indicates the company's eagerness to compete directly for long distance dollars with American Telephone & Telegraph Co. and its newer competitors such as MCI Communications Corp., at present the leading competitor for the multibillion dollar long distance business market.

SBS, a partnership of Communications Satellite Corp., International Business Machines Corp. and Aetna Life & Casualty, was founded primarily to develop highly sophisticated business satellite data and televised conference services. Until recently, the three partners have said little about using their satellite network for conventional long distance services.

The company was founded in 1975, with available initial funding of close to $1 billion, and its partners have been suffering losses trying to get SBS off the ground. Not until this year did the company begin receiving revenues from its initial business customers.

The filing with the Federal Communications Commission on long distance service, however, indicates that this particular business, which company officials expect to represent about 40 percent of SBS sales, will quickly soar. The service will not begin until February, but in 1982 alone SBS is predicting sales of $34.3 million.

But that figure will nearly triple in 1983 to $102 million and rise to $173.7 million in 1984, the company believes. Because of the heavy start-up costs of the program, the company predicts that the voice services phase of the SBS business will lose $32 million next year, before making a profit of $110,000 in 1983, and then a profit of $20.9 million in 1984.

SBS will beam the telephone calls off one of its two satellites now in orbit. Callers will link up directly through private lines from their businesses to earth station sites in major cities.

SBS officials are enthused about the their prospects in the enormous long distance telephone market, even though their network is initially limited to outgoing calls from 20 major metropolitan areas, including Washington. Initially only 18 cities will have access to the system, although the service can route calls throughout the United States.