What everyone else said, plus.
If you are on different servers, even if your standing in the same "room" you will not see or interact with each other. So if your trying to meet a friend in the game for the first time to get them on your "Friends" list for example, make sure they join the same server to meet you in the same room.
If you teleport to a Friend, Guildmate, Crewmember, you will be switched to the same server they are on.
So if you joined a quiet server on purpose, you might ask your friends to join you, instead of you joining them.
Zeppers lvl40
http://pirates.teamofx.us