This is directly based on the formula n*( n-1 )/2. If n is the number of stakeholders in the project, the total possible communication channels = n*( n-1 )/2. The project has 25 team members, 3 team leads, 3 support team members, and the Project Manager. That makes it 32 people and 496 possible communication channels. Please Refer PMBOK® Guide - Fifth Edition, Project Communications Management, PN 292.