The Telecommunications Information Networking Architecture (TINA) provides the architectural basis for the realization of telecommunications services as distributed applications. In particular application of distributed systems, new security problems arise. We discuss threats that are caused by the interruption of service control connections. A method to detect interruptions is presented and the handling of interruptions is described. The detection method is based on a cryptographic protocol using sequence numbers and probe messages. TINA and its security approaches are introduced. The threats by interruption are illustrated using a toll fraud example. Keywords: TINA, Connection Integrity, Security States, Sequence Numbers, Probe Messages