ABSTRACT:
As Common Channel Signaling (CCS) networks have continued to evolve, and network interconnection architectures and the services they support have grown more complex, it has become necessary to identify the type of behavior all network providers are expected to exhibit when specific requirements do not exist. GR-905 provides Interconnecting CCS Networks (ICNs) and other interconnecting networks (e.g., Session Initiation Protocol [SIP]-based networks; Bearer Independent Call Control [BICC]-based networks) with the Telcordia view of critical compatibility information required for successful network interconnection with client company CCS networks. These ICNs include Interexchange Carriers (IXCs), International Carriers (INCs), and Other LATA Carriers (OLCs) such as Independent Local Exchange Carriers (ILECs) and Wireless Service Providers (WSPs).

GR-905 includes the interface architecture and interface protocol messages, signals, conditions, and events that occur to support the exchange of information between CCS networks and other interconnected networks. In addition, GR-905 describes the physical interconnection; performance objectives; and provisioning, operations, maintenance, and network compatibility testing necessary to allow CCS networks to interconnect successfully.

GR-905 also provides important information for providers of Legacy Network Gateway and Legacy Selective Router Gateway systems to support the delivery of emergency calls between legacy origination networks and IP-enabled PSAPs, as well as emergency calls routed via Emergency Services IP Networks (ESInets) and legacy PSAPs that are served by Selective Routers.

Issue 22 provides the following updated information:

• Appendix K, IP Multimedia Subsystem (IMS) Overview, has been updated to describe in detail the procedures for processing callback calls in an IMS-based NG9-1-1 Emergency Services Network. Considerations for updating the protocol and procedures supported by IMS originating networks to allow multiple pieces of location to be delivered to an NG9-1-1 Emergency Services Network with an emergency call are also discussed.
• Appendix L, Network Interconnection to Support the Delivery of Legacy Emergency Call Originations to IP-Enabled PSAPs, has been updated to align with terminology used in the draft National Emergency Number Association (NENA) i3 Version 3 standard.
• Appendix N, SS7-Based Interconnection Between Emergency Services IP Networks and Legacy Selective Routers to Support Emergency Call Delivery and Transfer, has been as been updated to align the terminology and procedures with the current work going on in NENA related to the development of the NENA i3 Version 3 standard and the Legacy Selective Router Gateway standard.
• Appendix O, Support for Text to 9-1-1, has been restructured to put the regulatory information up front and to distinguish between Short Message Service (SMS) Text to 9-1-1 and Real Time Text (RTT) to 9-1-1. New text was added to the regulatory section to discuss FCC activities related to support for the transition from Teletypewriter (TTY) to RTT, and in particular, the ability for Commercial Mobile Radio Service (CMRS) providers to support RTT in lieu of TTY technology in wireless IP networks. A new subsection was added to describe RTT-TTY interworking details.
• Appendix P, Improved Location Accuracy for Wireless Emergency Callingdescribes extensions made to the Alliance for Telecommunications Industry Solutions (ATIS) National Emergency Address Database (NEAD)-based heightened location accuracy architecture to support access to External Location Services. This appendix describes the impacts on the functional elements and interfaces that comprise the base architecture, as well as the new functional elements and interfaces required to support access to External Location Services.
• A new appendix, Appendix Q, Enhanced Location-Based Routing of Emergency Callshas been added to describe alternatives for supporting enhanced location-based routing of emergency calls. This appendix discusses the use of Device-Based Hybrid (DBH) location delivered to CMRS Core Network elements via a Location Interworking Function to support location-based routing of emergency calls. It also considers using the existing location acquisition architecture in combination with signaling enhancements to support the use of the LTE Positioning Protocol (LPP) early location fix mechanism to acquire location to support the routing of emergency calls.