From the Wookieepedia post on Hyperspace:
In addition to navigational hazards, there was also the difficulty inherent in communicating with a starship while traveling at hyperspeed. Since ships in hyperspace did not exist, in a conventional sense, they were largely cut off from conventional radio or subspace communication, since wavelengths of any signal would be massively distorted even if they reached the vessel. Hypercomm signals could reach a vessel in hyperspace, however it was very difficult to communicate in even this fashion unless the signal was sent from one end or the other of the traveling ship's course, or between ships on the same course.
And further below:
Hypercomm technology sent signal packets through hyperspace at greater speeds and distances than was possible with more conventional subspace transmitters, and this was done so with much greater speed than hyperdrive-equipped starships. The HoloNet increased the range still further, using an interconnected network of hyperspace beacons to rebroadcast enormous tracts of data over the entire galaxy, allowing instantaneous, full-holo transmissions from virtually any subscriber to any other. Under the Galactic Empire, the HoloNet was rigorously controlled, and even under the New Republic, the network was fantastically expensive to maintain, and so direct two-way connection was usually limited to government personnel and the wealthy.
There are lots of links to devices and technology involved in the process, but I won't belabor you with my findings. Suffice it to say that, according to what I found, communication while traveling is a very tricky business, even for the most resourceful entities such as military and government. However, it doesn't surprise me if this little rule isn't always enforced in order to serve the plot. If they do it on Clone Wars, then that's evidence to support that the Wookieepedia articles can perhaps be ignored...
Damn. . . I just realized I missed the chat night. . .
Yeah man, we missed you!
I completely spaced on that, sorry. I meant to go, I must have gotten distracted.
Don't stress it. I missed like two or three whole months, and they haven't kicked me out yet.
We haven't? Damn. I coulda sworn . . .
Now be nice, Ice.
Course, saying that to Ice is like trying to tell a kid on a sugar-high to sit still...
Good to see you're still alive Gibson. . . I hadn't seen you in a while.
Indeed it has been too long. I will be back to posting soon by trying some of those things they taught me in high school English class. Hoping I remember it right, it was a looong time ago.
By the way, Ice. Loving what's happening between Reil and Calli! A nice normal relationship filled with love and pain.
Well, love isn't all wine and roses. Sometimes it's handcuffs and cheese.