Unrelated to the UNSC Fleet Command, the Covenant Fleet Communication channel, part of the Covenant Battle Network, is intended for broadcasts across an entire fleet, rather than between a pair or more of ships. It seems to be the equivalent of the UNSC's FLEETCOM 7. [1]
It is similar to the INTERSHIPCOM, albeit on a much grander scale.
It should be noted that because of its scale and ability to broadcast over the entire Covenant Fleet, it most likely has a restricted use only to Prophets and very high ranking Elites.