Satellite Business Systems will announce plans today to provide joint high-speed communications service with British Telecom, marking the fledgling company's first venture into international business.

Although SBS must receive Federal Communications Commission approval to enter the international field, the two concerns have agreed to develop a number of advanced communications services, principally high-speed digital services, such as data communications and electronic mail.

In a joint announcement, the two companies also said they would provide teleconferencing services, enabling businesses and others to conduct transatlantic meetings over television. The international services could begin as soon as this year, SBS said.

SBS President Robert Hall said the company's customers, many of which have overseas operations in Great Britain, had expressed strong interest in international services. There is more telecommunications traffic between the two countries than between the United States and any other nation, making SBS's entrance into that market particularly attractive.

"For our customers, it opens an opportunity to extend many advantages of their integrated domestic networks to their operations in the United Kingdom, enhancing the efficiency, the timeliness and the economy of their telecommunications," Hall said in a prepared statement. Sir George Jefferson, chairman of British Telecom, called the proposal a "major enhancement of transatlantic comunications services."

SBS is a McLean-based partnership of Aetna Life & Casualty, International Business Machines Corp. and Communications Satellite Corp. (Comsat) that is prepared to spend close to $1 billion to develop a satellite voice, data and video communications system for businesses and other institutions. After a series of delays, customers began receiving service from SBS earlier this year.

British Telecom, the government-controlled telecommunications monopoly that serves all the nation's telephones, is going through a series of major changes designed to bring competition into the business there and enable the company to enter new fields.

"SBS is pioneering the introduction of small-dish digital satellite business systems in the U.S., and our agreement with them will secure for BTI's multinational customers the service advantages of direct links with their U.S. establishments connected to the SBS system there," said Jim Hodgson, managing director of British Telecom International.

In requesting authority to enter the international field, SBS said the services would improve the U.S. competitive position in foreign markets by cutting travel costs and increasing productivity.

The companies said they would use existing Intelsat satellites for the international services. SBS also requested FCC approval for plans to use Comsat facilities in West Virginia and Maine as gateways for the international transmissions.