A Call Plan tells the system how to route phone calls when someone calls one of the numbers setup in your system. One Call Plan is assigned to each phone number in your system.
Within a Call Plan you can set your Business Hours. Once you have your Business Hours set, you can set different routing rules based on Business Hours compared to Closed Hours.
With the Enterprise version of Pulse, a company can create multiple call plans.
With the Pro version of Pulse, a company can create one call plan.
With the basic version of Pulse, call plans are not used.