| Term | Definition |
| ALI | Automatic location Identification: A database that relates a specific telephone number (TN) to an address. This database accepts a PSAP query with a TN and responds with an address. In the case of an ESQK, the ALI database steers the query to the appropriate VPC and steers the response back to the PSAP. An ALI is typically owned by a LEC or a PSAP. |
| ANI | Automatic number identification: Telephone number associated with the access line from which a call originates. |
| CBN | Callback number. The VoIP subscriber's telephone number. |
| CRN | Contingency routing number. A 10-digit, 7x24 PSAP emergency telephone number. Used for fallback routing if a call cannot be routed through the selective router to the PSAP. |
| ESGW | Emergency services gateway. A component, residing in the VoIP service provider's network, responsible for integrating the SIP network with the emergency services network and routing 9 1 1 calls to the appropriate selective router, based on the ESRN/ESQK it receives from the regional call server or the 9 1 1 call server. |
| ESQK | Emergency services query key. A digit string that uniquely identifies an ongoing emergency services call and is used to correlate the emergency services call with the associated data messages. It may also identify an emergency services zone and may be used to route the call through the network. Similar to an ESRK in wireless E9 1 1 networks. |
| ESN | An ESN is a three to five digit number representing a unique combination of emergency service agencies (Law Enforcement, Fire, and Emergency Medical Service) designated to serve a specific range of addresses within a particular geographical area, or Emergency Service Zone (ESZ). The ESN facilitates selective routing and selective transfer, if required, to the appropriate PSAP and the dispatching of the proper service agency (ies). |
| ESRN | Emergency services routing number. A 10-digit number that specifies the selective router to be used to route a call. |
| First responder | Police, fire, or medical resource who is dispatched to handle 9 1 1 calls and deliver emergency services. |
| I2 | NENA defined VoIP E9-1-1 solution. I2 routes VoIP calls into the current E9-1-1 systems and to the correct PSAP with correct ANI and ALI. I2 accommodates both stationary and nomadic users and provides MSAG valid location information and provides a method for nomadic user location either through an automated process or user input via a service prompted web based form or equivalent. Intended migratory path from i1. |
| I3 | NENA defined VoIP phase E9-1-1 solution. Also referred to as Long Term, Next Generation 9-1-1
Enables end to end IP based E9-1-1 design, supporting VoIP originated call delivery and the transition of current wireline and wireless service providers to IP interface technology. Support IP mobility users, and all capabilities of I2. Utilizes extended capabilities of IP to provide location and other information with the call, as well as other sub-sets of relevant |
| LEC | A Telecommunications Carrier (TC) under the state/local Public Utilities Act that provide local exchange telecommunications services. Also known as Incumbent Local Exchange Carriers (ILECs), Alternate Local Exchange Carriers (ALECs), Competitive Local Exchange Carriers (CLECs), Competitive Access Providers (CAPs), Certified Local Exchange Carriers (CLECs), and Local Service Providers (LSPs). |
| Mobile subscriber | A subscriber who uses a wireless device that can be in motion during the call. Wireless Fidelity (WiFi) VoIP is expected to eventually allow the end user to take a home-based telephony connection and roam within an interconnected wireless network, much as cellular technologies allow today. |
| MSAG | Master street address guide. An MSAG ledger is used by a municipality to assign a particular police, fire, or rescue agency to a given street and number range. |
| Nomadic subscriber | A subscriber who uses a device that is static during a call but does not have a static IP address assigned to it. Nomadic subscribers use Internet Service Provider (ISP) VoIP, which allows the end user to establish a telecommunications connection wherever he or she can obtain an Internet-based connection to her ISP provider. |
| PSAP | Public safety answering point. A PSAP is the endpoint of an emergency services call. PSAPs are responsible for answering emergency services calls (as defined in TIA J-STD-036). |
| SIP | Session Initiation Protocol. SIP is the IP-based protocol defined in IETF RFCs 3261 and 2543. SIP is one of two dominant messaging protocols used by the VoIP industry. |
| S/R | Selective Router. The node in the emergency services network that performs enhanced call routing for 9 1 1 calls. Usually operated by the LEC. |
| VoIP | Voice over Internet Protocol. VoIP is a system for providing telephone service over the Internet. |
| VoIP provider | A generic term to describe a company that provides VoIP call services. Some VoIP providers provide direct service to the consumer (VoIP service providers). Others provide backbone and PSTN access services (VoIP carriers). Still others provide ESGW (ESGW operators). Some VoIP providers provide more than one of these services. |
| VPC | VoIP positioning center. The application that determines the appropriate PSAP, based on the VoIP subscriber's position, returns associated routing instructions to the VoIP network, and provides the caller's location and the callback number to the PSAP through the ALI. |
*This glossary was created with supporting content provided by the NENA Master Glossary of 9-1-1 terms.
The complete glossary can be found at:
http://www.nena.org/9-1 1TechStandards/Standards_PDF/Master%20Glossary.pdf
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