How should we handle difficult firing meeting?

Q. We recently decided to terminate an employee based on performance concerns. The employee is in sales and is required to cold call a certain number of individuals each day. In reviewing the daily call logs, the employee’s manager discovered that she has been calling the same disconnected number over and over again ... To top it off, she sent an email telling other employees they could do the same. In preparing for the termination meeting, I’m wondering what we should say?