System and Method for assisting in controlling real-time transport flow through multiple networks via media flow routing

A system for controlling real-time transport protocol flow through multiple networks via media flow routing, comprising a first network that couples a first session router to a SIP proxy server and a transport network that couples the first session router to a second session router, wherein each of said first session routers comprise software to perform the steps of: - receiving a SIP Invite message; - performing an inbound screen on route information received from said second session router, to determine if said received route information should be discarded; - retaining in a local telephony routing information database (TRIB) all distinct routes described by received route information, each distinct route having the same degree of preference; - if said route information is not discarded, comparing said received and screened route information to a local policy defined within said first session router; and, - selecting a primary route from said received route information and local route information in accordance with said local policy, wherein said primary route is a path from said first session router to said second session router via said transport network.