Talk is cheap—in fact, it’s free in the game. A creature can talk as a free action, which means that it can speak even on another creature’s turn and as often as it likes (within reason), as long as it’s able to take free actions.

         Action: Free action.
         No Extended Monologues: A creature can speak freely using this action, but the Dungeon Master can limit the length of a monologue or a conversation that takes place during combat.
         Includes Other Communication: Creatures that communicate using telepathy or other forms of nonverbal communication also use this action to communicate.

Published in Rules Compendium, page(s) 251.