A transit domain is a domain in which trusted communications are generally required, and a foreign domain is one in which any number entities are associated. The users within a foreign domain will have a trusted relationship with their foreign domain. In turn, the foreign domain will establish a trusted relationship with the transit domain. The users in the foreign domains need not have a direct relationship with the transit domains. The foreign domains are connected by the transit domains, and session messages used to establish and control communication sessions between entities must pass through the transit domains to travel from one foreign domain to another. These session messages intended for or originating from a foreign domain are processed by edge control nodes in the transit domain, based on a service policy, which has been established for the foreign domain associated with the session message.