A method of operating a network by sharing resources associated with various classes among calls in the various classes according to a state dependent reservation parameter. Nominal amounts of one or more resources are allocated to each call class. When a call of a class of service operating in the network requires resources in excess of those allocated to the class, resources allocated to other classes of service are advantageously shared with the class of service. The sharing is based on a reservation parameter associated with the class of service of the call. The reservation parameter is advantageously a function of the network state. The role of the reservation parameter is to protect underloaded classes (i.e., those classes not using all of their allocated nominal capacity) from excessive borrowing by overloaded classes (i.e., classes using more than their allocated nominal capacity). More generally, the inventive method is used to determine if sufficient resources are available for routing calls and to route calls based on the determined available resources.