It's a "Our company has sufficiently-complex software that we sell to customers that pay us enough money to justify calling in one or more programmers outside of regular business hours to help handle problems that one or more of those customers considers Very Serious that our (IME often very, very knowledgeable) support staff can't figure out." thing.
It's a "Our company has sufficiently-complex software that we sell to customers that pay us enough money to justify calling in one or more programmers outside of regular business hours to help handle problems that one or more of those customers considers Very Serious that our (IME often very, very knowledgeable) support staff can't figure out." thing.