were the first Starfleet
vessels to carry subspace radio
transceivers. They were in service beginning in 2194
. (The Starfleet Museum
Prior to the development of the transtator in 2185, only specialized communications ships were powerful enough for the large arrays needed to transmit subspace signals.
- This is consistent with TOS: "A Piece of the Action", where it is recounted that Horizon didn't have subspace communications capabilities in the 2160s. But it is inconsistent with Star Trek: Enterprise, where the NX-01 did have those capabilities.