[Vidmaster]

even if it's silly and against all physical laws, (inter-dimensional radio ) yes it's possible in B5.

[LeGuille]

On that note: What of internet-type communications? Like surfing the interstellar web. I remember when Sheridan sent a comminque to a Minbari ship waiting in Hyperspace. So, is it supposed that once every so often they update the 'internet' for each sector independently via the gate? If that is so, then in hyperspace information is floating around, waiting to be sent out. Or is there a receiver attached to the gates that picks it another way? Since I know they can communicate to ships in Hyperspace, do they need to open up a hyperspace jump to receive the signal?

Or is it just like it is now, and is constantly linked on a hyperspace wireless signal?

[Demitri]

I could be wrong, but didnt b5 have to open the jump gate to summon the 2nd minbari warship in the epsiode with the trigati?

[Daeron]

I think they had to open the gate that time because they wanted to use an especially strong signal to make sure it could be picked up by anyone. Sheridan knew the second Minbari warcruiser had to be somewhere in subspace around that region.

Regular communication through hyperspace beacons wouldn't cut it in this particular case.

[-Norbert-]

Before sending the message Sheridan asked Ivannova if she could send the message without the Tragati intercepting it.

My guess would be, it was an optical message rather than a radio message and thus can only be read by being in the path of it (at least in real space).
In Hyperspace the laser (or whatever it was) would most likely then travel in a straight line, which should make it travel along the beacon, which is the logical waiting place for the Minbari cruiser.
Unless Hyperspace somehow refractures light (or whatever the beam was made up from), in which case the message would be shorter range, but could be received in a larger area, probably cone shaped away from the jumppoint.