Method and system for performing a least cost routing function for data communications between end users in a multi-network environment

Claim 1

In a multi-network environment including both private and public networks interconnected to each other via network nodes and links, a method for setting up a communication path for an end-user connected to a private network and calling an addressable target component accessible to said calling end-user via a public network, said addressable target component identified by a numerical or alphanumerical address, said method comprising: storing, at network activation time, in each node of the private network, a directory having routing information including the numbers or prefixes of numbers of public network attached resources accessible through said private network node; receiving a source call from a calling end-user at an entry node to the private network, said source call including a called target number of a called end-user; checking in the private network entry node, for the calling end-user, whether the called target number or a corresponding prefix of said called target number is stored in said entry node routing information; and, if stored, setting a path to the called target number through the private network using routing information associated with the longest prefix in the directory matching the called target number; otherwise causing said entry node to broadcast a query for the called target number to the remaining nodes in the private network; searching, in each directory of the queried private network nodes, for the called target number or prefixes of said called target number, and sending any corresponding detected numbers or prefixes to the entry node; monitoring the answers to said query in said entry node, checking for a best match; and, setting the path to the public network through the private network nodes which provided the best matching answer to the broadcasted query.