Interoperable routing for IN and IP Telephony

This paper discusses the problem of interoperability of IP Telephony and Switched Circuit Networks in the area of routing information. We describe and analyze a solution for directory-based routing. We will present an architecture based on a distributed database on the switched circuit network and the IP network. The aim of the solution is to provide efficient service management, close to optimal routing for all calls including calls to 800and cellular numbers and personal number portability between both network technologies. The solution is based on similar but differing in detail approaches for each network. In the IP network we use the Telephony Routing over IP (TRIP) protocol developed by IETF. Additionally, the described architecture is open for inclusion of the Telephone Number Mapping (ENUM) protocol that is under development. For the circuit switched network, we suggest a new protocol called Circuit Telephony Routing Information Protocol (CTRIP). The protocol provides a distributed method for synchronizing routing information between databases. Furthermore, we propose numbering gateways for transferring number information between the two network types. We utilize the Server Cache Synchronization Protocol (SCSP) as the common element for data synchronization and replication among distributed entities. We also discuss briefly the design of a test implementation of the proposed infrastructure functions and protocols under development in our Laboratory. In conclusion, we propose to design a common interoperable routing information infrastructure for the emerging hybrid SCN/IP Telephony network.