Are people ready to make money from the use of  IM?  Think of these scenario:

Ms. Legal is an attorney, when she answers an IM call from an inquirer, she should be compensated for the time she spend and the value of her consultation. So, she can price herself at $5 per minute in the Charge-to-Answer^SM section of the IM yellowpages, competing with her peers who rate themselves according to their own policies.  In this case, fee flows from caller to the callee (receiver).

When Mr. Bored retires and moves to Dallas, he enjoys Gardening to pass time, so he could list himself in the Pay-to-Answer^SM listing and offer like 15 cents per minute to encourage people to call him to chat on this subject.  In this case, fee flows from callee (receiver) to caller.