Don't confuse phasing with server shards. "Phasing", or "layering", happens within a server instance and determines how you see the world based on quest progression. You can enter and leave different phases by moving around the world, and may see players pop in and pop out as they enter different phases to you. "Shards" or "channels" are the different server instances that the game creates to maintain the population. If you're in a different shard to another player, the only way to see them is to /traveltoplayer to enter the same shard as them. From what I remember, Zone chat works across phases, but not across shards.And PvE zones have phasing anyway, which is a form of instancing.