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The three-digit telephone number that has been designated as the "Universal Emergency Number," for public use throughout the United States to request emergency assistance. It is intended as a nationwide telephone number giving the public direct access to a Public Safety Answering Point (PSAP) which will be responsible for taking the appropriate action.

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ALI (Automatic Location Identification)

A 9-1-1 Feature by which the name, address and responding agencies associated with the number of the telephone used to dial 9-1-1 is displayed at the PSAP at the time the call is answered.

ARIN (American Registry for Internet Numbers)

A non-profit organization established for the purpose of administration and registration of Internet Protocol (IP) numbers.


The Auto Attendant is a powerful and flexible tool to field inbound calls and deliver them to the intended destination through interactions with the caller.

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BAN (Billing Account Number)

Billing Account Number

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CAC (Carrier Access Code)

A dialing sequence used by the general public to access a preferred provider of service.

Calling Records

The CPUC considers calling records to be the records of calls made from a subscriber's telephone no matter how recorded and regardless of whether such information appears in the subscriber's monthly telephone service bill.

CARE (Customer Account Record Exchange)

The process of exchanging customer account information between local and long distance carriers. Every time a local carrier signs up a new customer, or every time an existing customer changes their PIC code, thereby changing their long distance carrier, the local carrier is responsible for notifying the long distance carrier. This applies even when the customer is keeping their current LD carrier while changing local carrier: the local carrier is still supposed to notify the LD carrier.

CCB (Common Carrier Bureau)

A branch of the FCC that monitors the telephone industry.


A varied way of acquiring PBX service - all switching occurs at a local telephone office instead of on a company's site.

CLC (Competitive Local Carrier)

The same thing as a CLEC.

CLEC (Competitive Local Exchange Carrier)

Any company or person authorized to provide local exchange services in competition with an ILEC. The CPUC's (California Public Utility Commission's) official definition is " Competitive Local Carrier (CLC) means a common carrier that is issued a Certificate of Public Convenience and necessity (CPCN) after the effective date of July 24, 1995, to provide local exchange telecommunications service for a geographical area specified by such carrier. There are two CLEC types: Facilities-based and Non-facilities-based, see definitions.

CLLICODE (Common Language Location Identifier)

A code, which identifies a customer at a physical address. (All codes are of an abbreviation for the city, state, an identifier for that particular building, and an identifier for the customer on a particular floor.)

Communications platform

The structure or standard needed to support communications, the transmission of data between two points, either by telephone or computer or integration of both in a PBX system.

CPCN (Certificate of Public Convenience and Necessity)

A certificate that must be filed by every CLEC with the CPUC.

CPE (Customer Provided Equipment)

Customer Provided Equipment


Formats, applications or devices that work on different or multiple platforms.

CSR (Customer Service Representative)

Customer Service Representative

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DID (Direct Inward Dialing)

A service offered by telephone companies which allows the last 3 or 4 digits of a phone number to be transmitted to the destination exchange.

For example, a company could have 10 incoming lines, all with the number 234 000. If a caller dials 234 697, the call is sent to 234 000 (the company's exchange), and the digits 697 are transmitted. The company's exchange then routes the call to extension 697. This gives the impression of 1000 direct dial lines, whereas in fact there are only 10. Obviously, only 10 at a time can be used.

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E-911 (Enhanced 9-1-1)

A method of routing 911 calls to a Public Service Answering Point that uses a customer location database to determine the location to which a call should be routed. E-9 .1 .1 service includes the forwarding of the caller's Automatic Number Identification (ANI) to the PSAP where the ANI is used to retrieve and display the Automatic Location Identification (ALI) on a terminal screen at the answering Attendant's position displaying name, address, and telephone number. It usually includes selective routing.

End Carrier

The local carrier who terminates the call to the end user.

Enterprise System

A business organization that generally relies on computers and internally- linked computer networks or systems to do business.

EUCL (End User Common Line Charge)

pronounced "eucal" or ewwwcals

A FCC tariff term defined in FCC Rules 69.104 as follows: "A charge that is expressed in dollars and cents per line per month shall be assessed upon end users that subscribe to local exchange telephone service, Centrex or semi-public coin telephone service to the extent they do not pay carrier common line charges. Such charge EUCL shall be assessed for each line between the premises of an end user and a Class 5 office that is or may be used for local exchange service transmissions. Each Single Line Service is charged one CALC or EUCL. The amount varies by state."

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Fault tolerance

A system's dependable and favorable response to unpredictable hardware or software failure. Levels of tolerance range from low - continued operations to high - mirrored operations capability guaranteed by a duplicate backup system. For example, in case of power failure on one computer, telephone or system, another can take over.

FCC (Federal Communications Commission)

The government agency that regulations telecommunications and other broadcast medium. www.fcc.gov

Follow Me Calling

Calls that one may have routed, or forwarded, to another telephone number.

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IDS - Intrusion Detection System

A security function that monitors all inbound and outbound network activity. It looks for suspicious patterns that may indicate a network or system 'hack' or attack. It follows an alert procedure, reducing risk of system attack or compromise.

IEC (InterExchange Carrier)

Refers to a Long Distance Carrier. IXC is another term.


Communications between states.


Communications inside one state.

ISDN (Integrated Services Digital Network)

A standard digital network that lets users send voice, data and video over one telephone line from a common network interface.

IXC (InterExchange Carrier)

Abbreviation for any long distance carrier. IEC is another abbreviation favored by LECs.

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LAN (Local Area Network)

A data communications network that is geographically limited (typically to a 1 km radius) allowing easy interconnection of terminals, microprocessors and computers within adjacent buildings. Ethernet and FDDI are examples of standard LANs.

Because the network is known to cover only a small area, optimizations can be made in the network signal protocols that permit data rates up to 100Mb/s.

LOA (Letter of Agency)

This is exchanged between telecomm companies, or between a customer and a telecomm company granting permission for the receiver to install telecomm service to the sender.

Local Loop

The local loop is the telephone line that runs from the local Telephone Company to the end user's premise. The local loop can be made up of fiber, copper or wireless media. Same as local exchange loop facility whose formal definition is "known as a basic level network access channel, local exchange loop facility means a transmission path capable of delivering analog voice grade signals or digital signals at less than 1.544 Mbps between the network interface at a customer's premises and the main distribution frame or any other point of interconnection to the LEC network."

LRN (Local Routing Number)

A 10-digit code that represents a specific carrier. This code is "attached" to each phone number to indicate which "carrier" the phone number currently is subscribed with for routing purposes. Created for the LNP process, when a customer switches carriers, the new carrier's LRN replaces the old.

LSO (Local Serving Office)

Local Serving Office

LSP (Local Service Provider)

A term intended to encompass all companies providing dial tone to end users, including but not limited to Incumbent Local Exchange Carriers (ILEC), Alternative Local Exchange Carriers (ALEC) and Private Branch Exchange (PBX) providers.

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MPOE (Minimum Point of Entry)

Minimum Point of Entry

MSAG (Master Street Address Guide)

A listing of all streets and number ranges within a 9-1-1 service area. The streets and address ranges are assigned routing codes, or emergency service numbers (ESNs), to enable proper routing of 9-1-1 calls.

Multiplexing or Mux

Multiplexing is a technique whereby multiple devices can share a telephone line. With multiplexing, users do not have to lease individual telephones for each computer that wishes to communicate. T-1 multiplexers enable 24 devices to share one telephone line.

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NAT (Network Address Translation)

A hardware device currently being developed and used to extend the Internet addresses already in use. NAT has been suggested as an alternative to adopting IPv6 (IPng). It allows duplicate IP addresses to be used within a corporation and unique addresses outside.

NID (Network Interface Device)

The point of demarcation between the end user's inside wiring and LEC's facilities. Same as a NIU (Network Interface Unit).

NIU (Network Interface Unit)

Same as a NID (Network Interface Device), it serves as the point of demarcation between the local exchange carrier network and the customer's premise. It is required to be placed at the MPOE (minimum point of entry) which is typically in the basement, first floor telco room, garage, or even outside the building. NIUs are multi-functional devices, which include a protector block to prevent high-voltage surges from affecting premise equipment and inside wiring. It also usually allows the carrier to initiate a loop-test back from the central office to test the integrity of the local loop. A local exchange carrier will never install an NIU at an extended demarc - this is in their tariffs.

Non-Facilities Based CLECs

Those CLECs which do not directly own, control, operate, or manage conduits, ducts, poles, wires, cables, instruments, switches, appurtenances or appliances in connection with or to facilitate communications within the local exchange portion of the public switched network.

Non-published Service

The CPUC considers non-published service to be when a subscriber requests that their name, address, and telephone number not be listed in any telephone directory, street address directory, or in the directory assistance records available to the general public (411).

NPA (Numbering Plan Area also called area code)

An NPA is the 3-digit code that occupies the A, B, and C positions in the 10-digit NANP format that applies throughout the area served by the NANP. NPAs are of the form NXX, where N represents the digits 2-9 and X represents any digit 0-9. In the NANP, NPAs are classified as either geographic or non-geographic.

NPAC (Number Portability Administration Center)

A center, which supports the implementation of Local Number Portability (LNP).

NPAC SMS (Number Portability Administration Center Service Management System)

NPAC's system that manages the porting of telephone numbers from one service provider to another.

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PBX (Private Branch Exchange)

PBXs are computerized on site telephone systems located at commercial premises. They route calls both within an organization, and from the outside world to people within the organization.


When used as a noun, a port (also known as a basic level network access channel connection) is the interface between the local loop and the appropriate LEC Central Office switching equipment.

PSAP (Public Safety Answering Point)

The central point where the 911 call is received and responded to.

PSTN (Public Switched Telecommunications Network)

The PSTN is composed of all transmission and switching facilities and signal processors supplied and operated by all telecommunications common carriers for use by the public. Every station on the PSTN is capable of being accessed from every other station on the PSTN.

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A job group or call line-up, or the process of how calls line up and wait to be handled.

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Rate Center (referred to as RRD in RDBS)

A geographically specified area used for determining mileage and/or usage dependent rates in the Public Switched Telephone Network. The geographic point is identified by a specific Vertical and Horizontal (V&H) coordinate that is used to calculate distance-sensitive end user traffic to/from the particular NPA-NXXs associated with the specific Rate Center. A rate center is not always the exact equivalent of an Exchange Area, but can be.

RBOC (Regional Bell Operating Company)

Refers to any of the "Ma Bell" local exchange carriers, such as Pacific Bell, Southwestern Bell, etc.

Resp Org

Responsible Organizations are entities designated to manage and administer a customer's Toll Free number using the SMS/800 system.

ROE (Right of Entry)

Right of Entry


A device, with routing intelligence, that connects parts of local and remote networks together. Because they use routing tables to look up addresses for each message, routers introduce delays into networks.


A telephone call's path from source to destination. Routing is usually managed by a router, which directs the call or message to pass from one monitor to another.

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How well a system adjusts to shifting demand. A scalable system for business means one that grows reflectively with the business, starts with basics but features upgrade options to meet greater business demands.


Interdependent people or things interacting to do work. System also describes a method for how work is done.

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TC (Technical Consultant)

A technical consultant from the marketing department.

Toll Free

When calling a Toll Free number (area code/NPA 800, 888, 877), the dialing party incurs no toll charges.

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Not real, but with Virtual PBX™, only in terms of equipment investment. The business exchange service is very real, an absolute.

Virtual PBX™

A business phone system that operates from a public-switched telephone system, without requiring customer-installed equipment. Integrated with existing equipment and public service, Virtual PBX? provides call routing, follow-me calling, voicemail, fax-mail and automatic call distribution queues.


VoIP, or Voice over Internet Protocol, is a technology that enables people to use the Internet as the transmission medium for telephone calls. Voice data is sent in packets through your high-speed Internet connection rather than by traditional POTS lines (Plain Old Telephone Service). VoIP is significantly less expensive than typical telephone long distance packages, plus one high speed Internet connection can serve for multiple phone lines with no loss in functionality, reliability, or voice quality.

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Wire Center

A building or space within a building that serves as an aggregation point on a LEC's network, where transmission facilities and circuits are connected or switched.

Wire Center can also denote a building in which one or more Central Offices, used for the provision of exchange services and access services, are located.

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