Rather than paying a support person by the hour to sit by the phone and wait for that user to call, spend the time to ship the support with the application in the form of a help system. If you're a developer and you can't be objective, hire someone to write the help for you. If you'll be writing your own help system, be excruciatingly brutal with your own work. When you have your application Alpha and Beta tested, have the testers also test the help system. And when the comments come in from these testers, throw your ego out the window and do what's necessary for the user.
Help is a required part of an application.
Many times, developers and managers alike make it the last thing on the list of items to be done. To be done right, help should be developed concurrently with the application itself, not as a rushed afterthought. Make your help system as complete as you possibly can, and when you've run out of things to include, realize that you've probably missed something, and go over all of it again. You'll definitely save money on the support staff in the long run.