A method of mediating message traffic across interfaces open to third parties in an Advanced Intelligent Network for a switched telephone system is disclosed. Network utilization is monitored by maintaining message counts at the open interfaces and rejecting messages or terminating access via the interface when an excessive rate of traffic is detected. Access to data bases stored in service control points is used to determine if the sender identified in the contents of the message is the same as the entity authorized to use the physical port upon which the message was received. Also, customer records in the service control point are tested to determine if the sender of the message is authorized to affect the call progress of an affected customer directory number identified in the message. Upon termination of the message traffic across a port, a default application is activated so that other network elements do not have to rely on timeouts to continue processing of calls.