Method and system for routing calls over a packet switched computer network

The present invention describes how a trusted network routing authority, such as a VoIP inter-exchange carrier or clearinghouse can provide routing and secure access control across multiple network domains with a single routing and admission request. This technology can improve network efficiency and quality of service when an Internet Protocol (IP) communication transaction, such as a Voice over IP (VoIP), must be routed across multiple devices or administrative domains. This technology defines the technique of performing multiple route look-ups at the source of the call path to determine all possible routes across intermediate domains to the final destination. The VoIP inter-exchange carrier or clearinghouse then provides routing and access permission tokens for the entire call path to the call source.