The same way it's possible for a graphics designer to outsource his or her own jobs to another person to work on is the same way others can outsource projects to him.
How's the pay you get from works which are outsourced to you by another graphics designer? How often do you receive outsourced jobs?
All my projects have been directly from the clients to me. I have never worked through outsourcing before. Though if I see that one as well I will surely work with it.