When two domestic communications satellites were launched into synchronous orbit during 1976, a new era in long distance calling began for the nation's phone customers. Relaying calls back and forth across the country, the satellites, called Comstar, were used jointly by the American Telephone and Telegraph Company and GTE Satellite Corporation, a subsidiary of General Telephone and Electronics. Designed to keep pace with the burgeoning growth of telephone usage in the United States, Comstar employed the new dual polarized antenna system. Each Comstar, which operates in the C-band frequency, is equipped with 24 transponders capable of relaying a total of more than 18,000 telephone calls simultaneously throughout the contiguous United States, Hawaii, Alaska, and Puerto Rico.