The European Telecommunications Satellite Organization (Eutelsat) has been servicing the European community since 1977, being formally established by a multi-lateral agreement in 1985.

In 1979 ESA agreed to design, build, and launch five ECS (European Communication Satellite) spacecraft to be assumed by Eutelsat after passing initial on-orbiting testing. At that time the name of each spacecraft was changed to Eutelsat 1-F1, Eutelsat1-F2, etc. Of the five ECS spacecraft, four were successfully launched (1983, 1984, 1987, and 1988) and transferred to Eutelsat. ECS 3 was lost in an Ariane-3 launch accident in 1985.

AMSAT P3B (Phase 3B) was a similar repeat of the former satellite. It carried two transponders. The Mode-B transponder receives in the 70 cm-Band and transmits in the 2 m-Band. It has a bandwidth of 150 kHz for 50 simultaneous connections. The Mode-L transponder receives in the 23 cm-Band and transmits in the 70 cm band with a bandwidth of 800 kHz for 300 simultaneous connections. In contrast to P3A, it carried a liquid bipropellant propulsion system featuring an S400 engine. After reaching a highly elliptical 12-hour orbit, it was renamed OSCAR 10 (AO 10). The satellite collided after separation with the upper stage, which affected the propulsion system, so the satellite could not change the inclination to 57°. The satellite lost attitude control in December 1986 but remained partially operational until 2003.