Encyclopedia Galactica: Gravity Radio
Radio waves are able to traverse warp space or the gravetic plane the same as physical objects like starships. Radio waves move at the same speed as starships, the speed being based on the volume of tachyon particles released when a comsat (communications satellite) is dropped into warp space. Most comsats are large and configured to broadcast radio waves at a rate of 8 parsecs per week, but smaller units can be built. The difference between a space radio and a starship is the radio wave does not have to emerge from warp space after a week. It will continue on until it reaches its aim point which can be as far away as the comsat has coordinates for.
So it is possible to communicate from one end of known space to the other (900 light years) in approximately 35 weeks. Not exactly instant communications but communications nonetheless.
