Elevator Music

While I was at work today (yes, after 8 months I got a job this week!) I had to make a call and was put on hold for quite a while as I waited for the next available agent.  The on hold music starts up and my mind starts to wander, who composes this stuff?  If their song gets played in an elevator or as the ‘while you wait music’, do they get paid for that?  Do companies have to buy the rights to the song?  I wonder if any of the composers have ever heard their stuff in an elevator or while they were on hold?  Just stuff I thought about while on hold.