Performance modeling of high probability call-completion features

The Government Emergency Telecommunications Service (GETS) provides authorized National Security/Emergency Preparedness (NS/EP) users enhanced public switched network (PSN) service in which GETS calls receive higher likelihood of completion then plain old telephone service (POTS) calls during events of severe network stress. The PSN enhancements have been engineered through a comprehensive process that included modelling the local exchange carrier (LEC) performance benefits of trunk queueing dynamic trunk reservation, off-hook waiting for outgoing trunks (OHWOT), alternate carrier routing (ACR), enhanced ACR and exemption from restrictive network management controls (NMCs). Basic analytical formulas are presented to model the different features to overcome trunk congestion and shown effective via event simulation validation. Development and application of an integrated analytical model combining the features to overcome trunk congestion with other features is then described. The results show that combination of LEC features is necessary to provide a high likelihood of GETS call completion over a broad range of calling patterns and stress conditions (including congestion at eight times overload) that would cause POTS calls to have a very low likelihood of completion.