On the live servers most chats were local except Party and Whispers. There was no universe chat. For that I reason I had to make use of one of the moderators to get people to my arena event. He could pop a window in the center of the screen to reach all the people on a shard because some had one channel on others on another,  and then he switched to the pve server to get people from there who had a char on the pvp server to come to it for the event.