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Trunking for Private Switch 9-1-1 Service
Full Name:
Trunking for Private Switch 9-1-1 Service
Document Type: Informational
Number: 03-502 v1

This NENA TID defines three distinct alternative trunking configurations to accomplish the provisioning of Private Switch 9-1-1 Service (PS/911) in conjunction with the use of Private Branch Exchange (PBX) telephone systems. For PBX systems that use digital trunks, Primary Rate Interface Integrated Services Digital Network (PRI-ISDN) trunks, the provisioning of PS/911 may be accommodated without the requirement of dedicated trunks for transporting 9-1-1 calls. For PBX systems that use analog trunks (i.e. they are not compatible with PRI and/or PRI trunks are not available from local service providers), the provisioning of PS/911 may be accommodated by using dedicated circuits that operate with the Centralized Automated Message Accounting (CAMA) signaling protocol.


There are two CAMA alternatives that can be implemented; connecting the circuit to the Selective Router or connecting the circuit to the PSAP. While this document recommends using the PRI alternative for PBX sites served by PRI trunks, it is recognized that technical issues, tariff issues, or local conditions may determine that the CAMA alternative must be used. This document discusses how these configurations may be implemented, along with the issues and benefits of each alternative.

This document also supports the NENA PS-ALI Model Legislation by describing three alternative means of implementing PS/911 that are currently available.

This TID is a guide for vendors and users of PBX systems, local service providers, 9-1-1 network providers, and 9-1-1 agencies to use in determining how to implement PS/911 in an efficient and reliable way.

Committee Name(s): Interconnection & Security

Created: 04/11/2003


Trunking for Private Switch 911 Service
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