Are they communicating telepathically? if so doesn't that mean the Villagers can't do it? since its sorta magic? Or is it like a cell phone... The idea of a fire giant running around slaying people while talking on his T mobile sounds kinda amusing.

Trujfeuy

from Help Tell....

"TELL sends a message to one awake player anywhere in the world. Though it can
be done over any distance, Therans consider this ability completely natural,
and something anyone can do. "

Sounds perfectly normal to me. It's a game, enjoy it don't analyze it too much.