Abstract :
Describes the development of two enhancements to the Digital Private Network Signalling System (DPNSS1) as specified in BTNR 188, to meet some specific operational requirements for private networks potentially handling emergency-type services. These are precedence & preemption, a feature to ensure the successful termination of calls through a congested or damaged network; and secondly secure call, a feature to provide indication of and protection of calls carrying classified information
