A series of subspace amplifiers were deployed by the Earth starship Enterprise during its initial exploratory mission. The amplifiers were deployed to allow better communication with Earth and United Earth Starfleet Command. The amplifiers were designated by letter-number combinations. The first such device, Echo One, was deployed in July of 2151, with Echo Two being deployed two months later. (ENT: "Fortunate Son") Starfleet Command Council held contact via subspace buoys with Enterprise while the ship was on its mission in the Delphic Expanse. (ENT: "Twilight")