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        An SS7 signaling link between a Signal Transfer Point (STP) and either a telephone switch (SSP)
        or a Service Control Point (SCP).

    Abbreviated Dialing
        A feature that permits the calling party to dial the destination telephone number in fewer than
        normal digits. Abbreviated Dialing numbers must be set up in advance of their use. Speed
        Dialing is a typical example of Abbreviated Dialing.

         The method, time, circuit, or facility used to enter the network.

    Access Code - AC
        A short sequence of digits allowing a user to access a specific facility, service, feature or
        function of a telecommunications network or computer system.

    Access Coordination
        The design, ordering, installation, pre service testing, turn-up and maintenance on local
        access services.

    Access Line
         The circuit used to enter the communications network.

    Access Node
        Switching equipment, usually placed in large buildings with multiple customers or at a single
        customer premise, and designed to handle large volumes of calls.

    Access Tandem - AT
        A LEC switching system that provides a traffic concentration and distribution function for
        inter-LATA traffic originating or terminating with a LATA.  The access tandem provides the
        IC with access to more than one end office within the LATA. More than one access tandem
        may be required to provide access to all end offices within a LATA.

    Account Codes
        Also known as Project Codes or Bill-Back Codes. Account Codes are additional digits dialed
        by the calling party that provide  information about the call. Typically used by hourly professionals
        (accountants, lawyers, etc.) to track and bill clients,  projects, etc.
    ACNA - Access Carrier Name Abbreviation
        This is how a telecommunications company is identified to others like it. Used on all access
        service requests when  ordering service from the LEC.  (e.g. Electric Lightwave's  ACNA is "ELG")
        There can be multiple CICs per ACNA.

    ACTL - Access Customer Terminal Location
        Identifies the COMMON LANGUAGE location where an Interexchange Carrier (IC) interLATA facilities
        are terminated for connection to an Exchange Carrier (EC) for Access Services. For a CLLI to be an ACTL,
        it must end in (x)MD or W(x)(x) with "x" being any number or letter.

    Address Mask
        A 32-bit long mask used to select an IP address for subnet addressing. The mask selects the
        network portion of the IP  address and one or more bits of the local LAN address.

    Address Translation
        The process of converting external addresses into standardized network addresses and vice
        versa. Facilities interconnection  of multiple networks which each have their own address plan.

        A person or organization that acts on behalf of another. In the telecommunications industry,
        Agents typically are independent  individuals or companies that market the services of a carrier
        as if they were employees of that carrier.

    Aggregate Discount
         A discount applied to multiple services based on the total dollar value of those services.

        An independent entity that brings several subscribers together to form a group that can obtain
        long-distance service at a  reduced rate. Subscribers are billed by the original IXC. The aggregator
        only provides the initial set-up of the plan. He usually provides no service after that. Different than
        a reseller.

    AIN - Advanced Intelligent Network
        A dynamic database used in Signaling System 7. It supports advanced features by dynamically
        processing the call based  upon trigger points throughout the call handling process, and feature
        components defined for the originating or terminating  number. Offers one way for a network element
        to query a central database to obtain local number portability routing  information.

    AIOD - Automatic Identified Outward Dialing
        An option on a PBX that specifies the extension number, instead of the PBX number on outward
        calls (for internal billing).

        Alarm indication signal usually all ones--F11111111. Also known as a Blue Alarm which signals
        that an upstream failure has  occurred.

        A real-time indication or signal of an abnormal situation or event, which triggers an audible, visual
        or other indication that  there is a problem with telecommunications equipment, facilities or building
        environment.  Usually includes a Priority  or Severity Code.

    Alternate Access
        A form of local access where the provider is not the LEC, but is authorized or permitted to provide
        such service.

    Alternate Access Carriers
        Local exchange carriers in direct competition with the RBOCs. Normally found only in the larger
        metropolitan areas.  Examples are Teleport and Metropolitan Fiber Systems.

    Alternate Mark Inversion - AMI
        A line code used for T-1 and E-1 lines that has a 12.5% ones density minimum, and the one
        conditions of the signal alternate  between positive and negative polarity.

    Alternative Operator Services - AOS
        Operator services provided by a company other than a LEC RBOC or AT&T that is authorized
        to provide such service.

    AMA - Automatic Message Accounting
        The automatic collection, recording and processing of information relating to calls for billing

    Analog Signal
        An electrical signal that varies continuously in amplitude and frequency and usually carries
        voice traffic.

    Ancillary Charges
        Charges for supplementary services comprised of optional features, which may consist of both
        non-recurring and monthly  charges.

    Ancillary Features
        Subordinate, supplementary, sub component characteristics and capabilities. Marketing options
        of Products and Services.

    ANI - Automatic Number Identification
        Originating Number
        (1) The number associated with the telephone station(s) from which switched calls are originated
        (or terminated).
        (2) A software feature associated with Feature Group D (and optional on Feature Group B) circuits.
        ANI provides the  originating local telephone number of the calling party. This information is
        transmitted as part of the digit stream in the  signaling protocol, and included in the Call Detail
        Record for billing purposes.
        (3) ANI may also be used to refer to any phone number.

    ANSI - American National Standards Institute
        A United States-based organization which develops standards and defines interfaces for

    Answer Supervision
         The off-hook indication sent back to the originating end when the called station answers.

    Application Program Interface - API
        Programmatic interface used for interprogram communications or for interfacing between protocol

        The specifications of a system and how its subcomponents interconnect, interact and cooperate.
        Architectures are often  described in multiple levels of abstraction from low-level physical to higher-level
        logical application and end-user views.

    Area Code Routing
         Route calls based on the originating ANI NPA (area code). See NPA-NXX Routing.

    Area of Service - AOS
        The geographical area supported by a communication service. For 800 numbers, if AOS is "CC", it
        is using Complex Call

    ARP - Address Resolution Protocol under TCP/IP
        Used to dynamically bind a high level IP address to a low-level physical hardware address. ARP is
        limited to a single physical network that supports hardware broadcasting.

    ART - Advanced Radio Technology
        A company that provides the use of a microwave dish installation at the customer's site to avoid the
        LEC portion of a local loop, and connects directly into ELI's network.

    ASCII - American Standard Code for Information Interchange
        A uniform code used in computer and data communications systems, which employs seven binary
        digits (bits) to represent all letters, numbers, punctuations and special characters, plus one parity bit
        used in checking for transmission errors.

    ASR - Access Service Request
        A document (or data transaction) sent to the LEC, CLEC, or IEC/IXC to order the local access
        (loop) portion of a circuit.

    Asynchronous (i.e. Not Synchronous)
        A form of concurrent input and output communication transmission with no timing relationship
        between the two signals.  Slower-speed asynchronous transmission requires start and stop bits
        to avoid a dependency on timing clocks (10 bits to  send on 8-bit byte).

    Asynchronous Transfer Mode Adaptation Layer - AAL
        A series of protocols enabling ATM to be made compatible with virtually all of the commonly used
        standards for voice, data,  image and video. AAL-1 = Functions in support of constant bit rate,
        time-dependent traffic such as voice and video.  AAL-2 =  A place holder for variable bit rate video
        transmission.  AAL-3/4 = Functions in support of variable bit rate, delay-tolerant data  traffic requiring
        some sequencing and/or error detection support.  AAL-5 = Functions in support of variable bit rate,
        delay tolerant connection-oriented, and connectionless, which have been combined.

    ATM - Asynchronous Transfer Mode
        An international ISDN high-speed, high-volume, packet-switching transmission protocol standard.
        ATM uses short, uniform,  53-byte cells to divide data into efficient, manageable packets for ultrafast
        switching through a high-performance  communications network. The 53-byte cells contain 5-byte
        destination address headers and 48 data bytes. ATM is the first  packet-switched technology designed
        from the ground up to support integrated voice, video, and data communication  applications. It is
        well-suited to high-speed WAN transmission bursts. ATM currently accommodates transmission speeds
        from 64 Kbps to 622 Mbps. ATM may support gigabit speeds in the future.

        A loss of signal strength in a lightwave, electrical or radio signal usually related to the distance
        the signal must travel (e.g. fiber optic transmission must be regenerated approx. every 30 miles).
        Fiber optic attenuation is caused by transparency of  the fiber, bending the fiber at too small of a
        radius, nicks in the fiber, splices, poor fiber terminals, FOTs, etc.EDOA),  Electrical attenuation
        is caused by the resistance of the conductor, poor (corroded) connections, poor shielding, induction,
        RFI, etc. Radio signal attenuation may be due to atmospheric conditions, sun spots, antenna
        design / positioning, obstacles,  etc.

    AuthCode - Authorization Code
        A number used for security purposes to gain access to an Interexchange Carrier's network.
        Authorization codes are  inherently required for all Feature Group-A and Feature Group- B
        Circuits without ANI reporting. Authorization codes are also  required for Travel Service and
        Cut-Through capabilities on Feature Group-D circuits.

    Automatic Call Distribution - ACD
        Service which allows automated routing and reporting of calls for customers with multiple stations
        or locations.  A system designed to evenly distribute heavy incoming call traffic among multiple

    Automatic Location Identification
        A 911 feature by which the name, address and responding agencies associated with the number
        of the telephone, used to dial 911, is displayed at the PSAP at the time the call is answered.

    Automatic Ring Down - ARD
        A private line connecting a station instrument in one location to a station instrument in a distant
        location with automatic  two-way signaling. The automatic two-way signaling used on these circuits
        causes the station instrument on one end of the  circuit to ring when the station instrument on the
        other end goes off-hook. This circuit is sometimes called a "hot-line"  because urgent communications
        are typically associated with this service. ARD circuits are commonly used in the financial
        industry. May also have one way signaling. Station "A" rings Station "B" when Station "A" goes
        off hook, but Station "B"  cannot ring Station "A".

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İVector Graphics 1995

Revised: February 16, 2011
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