The wormhole relay station was a subspace relay station that allowed communications from the Alpha Quadrant to pass through the Bajoran wormhole into the Gamma Quadrant between stardates 48543.2 and 50564.2.
Although communications through the wormhole were possible, it was unreliable and required the wormhole to be open while the transmissions occurred. Some attempts were made in 2370 to produce a reliable communications network that traversed the wormhole, but due to the wormhole's high interference, which consisted of unstable subspace carrier waves and high phase variances, the signal was not strong enough to pass through. Subspace communications that bypassed the wormhole could take over twenty years to reach the Gamma Quadrant.
The disastrous First Contact between the Dominion and the Federation created a growing need to have a reliable communications conduit to the Gamma Quadrant so that Dominion activity could be monitored.