There was mobile communication. Skywalker and C-3PO used a 'comlink' to communicate when Skywalker, etc. were in the garbage mashers. And the Storm Troopers use

There was mobile communication. Skywalker and C-3PO used a 'comlink' to communicate when Skywalker, etc. were in the garbage mashers. And the Storm Troopers use a comlink, which has a transmitter that breaks down often enough that the Command Office wasn't suspicious when TX-four-one-two couldn't respond. On Hoth, Skywalker on his Tauntaun uses a comlink to talk with Solo. And Solo uses a pocket comlink to talk with Transport to say that he and Leia have been blocked by a collapse of the ice corridor and will be using the Falcon to leave Hoth. There are other examples of comlinks used as practical mobile communication about equivalent to a compact walkie-talkie.