A Gamma Quadrant planet holding an unmanned Dominion communications relay, to which the Defiant is directed in The Search while trying to make contact with the Founders.
In The Search, Part I, set in 2371, Sisko takes the new USS Defiant into the Gamma Quadrant to find the Founders and convince them that the Federation is no threat. The Karemma, trading partners of the Ferengi, admit that their instructions from the Dominion come by way of a subspace relay on Callinon VII.
The relay station proves to be unmanned. Dax and O'Brien beam down, tap into its computer and learn where its outgoing signals are sent, but a security system traps them inside as Jem'Hadar ships approach.
Sisko has no choice but to leave them and take the cloaked Defiant onwards, a decision that weighs on him for the rest of the episode. The Defiant is soon attacked and boarded, and the crew are later reunited as prisoners of the Dominion in the second part.