A technique for reserving resources in a communication network for an entity. Communication units in the network register with policy data points (PDPs) to attain authorization to establish and receive calls in a communication network. The PDPs supply the communication units with security tokens that the communication units use to assert that they are authorized to establish sessions and reserve resources in the communication network. Communication units associated with a call include their tokens in signaling messages that are used to establish the call. Nodes along the path between a communication unit associated with a calling party in the call and a communication unit associated with a called party in the call use the tokens to authenticate the source of the signaling messages and determine whether they have permission to reserve resources in the communication network.