Telecommunications Glossary
All Telephone Terms

What does - best discount long distance services mean? Or how about:- 1+ long distance, calling cards, international service and call back services? What is an international dial around? What is the difference between a carrier and a provider? Every day technology advances and inevitably someone somewhere develops a new word, an abbreviation or an acronym about the communications industry. All these terms are detailed in our Telecommunications Glossary below. Now expanded to include Internet Telephony and voice over IP phone terminology! (There are a considerable number of terms in this glossary. Please be patient for a second or two while we load the information.)

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.
Access gateway	Equipment used to provide the electronic "bridge" from the public switched telephone network (PSTN) to an Internet protocol (IP) network.
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.
ADSL	Asynchronous Digital Subscriber Line.
Agent	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.
Aggregator	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.
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.
Alternative Operator Services	Operator services provided by a company other than a LECRBOC or AT&T that is authorized to provide such service.
ANI	See Automatic Number Identification.
Answer Supervision	The off-hook indication sent back to the originating end when the called station answers.
ARI	Automatic Room Identification (Hotel/Motel room number)
Authentication	Process of verifying with certainty the identity of a valid subscriber or ITSP through the use of a unique user identification number, password or other method (i.e., verifying that customers are who they say they are).
Authorization	Process of allowing a Subscriber or ITSP a certain monetary credit or time amount of IP Telephony. Authorization is the granting of permission to provide users the service they are requesting.
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 signalling protocol, and included in the Call Detail Record for billing purposes. (3) ANI may also be used to refer to any phone number.
Baby Bells	See RBOC Backbone
Ballot	A release form that authorizes a customer's long-distance phone service to be switched to (another) long-distance carrier, or reseller. Also know as a Letter Of Agency or LOA.
BAN - Billing Account Number	Used by telephone companies to designate a billing account, i.e., a customer or customer location that receives a bill. A customer may have any number of BANs.
Banded Rates	Tariffed rates which may be changed by the carrier within a specified range. Frequently, state commissions require notice to the commission prior to each change. Banded rates are being used less frequently today.
Bandwidth	Amount of data that can pass through a connection (such as a modem) in a given amount of time.
Bell Customer Code	A three-digit numeric code, appended to the end of the Main Billing Telephone Number, that is used by Local Exchange Carriers to provide unique identification of customers.
Bell Operating Company - BOC	The local (or regional) telephone company that owns and operates lines to customer locations and Class 5 Central Office Switches. BOCs have connections to other COs, Tandem (Class 4 Toll) offices and may connect directly to IECs like WorldCom, AT&T, MCI, Sprint, etc. BOC may refer to the nineteen Bell Operating Companies that are owned by the seven RHCs (Regional Holding Companies) (not including Cincinnati Bell or Southern New England Telephone). The BOC role was originally defined by the 1982 Modified Final Judgement that specified the terms of the AT&T Divestiture). For Example, the three BOCs: Mountain Bell, Northwestern Bell and Pacific Northwest Bell are owned by the U.S. West RHC. Each BOC may service more than one LATA, but BOCs are generally constrained from providing long distance service between LATAs.
Billing Account Number - BAN	Used by telephone companies to designate a customer or customer location that will be billed. A single customer may have multiple billing accounts.
Bill-To-Room	A billing option associated with Operator Assisted calls that allows the calling party to bill a call to their hotel room. With this option, the carrier is required to notify the hotel, upon completion of the call, of the time and charges.
Bit	The smallest data unit that a computer can handle.
Block Calls	Prevent calls from completing to the requested destination. May be due to network problems (outage, overload, etc.), or by customer request (e.g. block calls from-or-to certain NPAs, NXXs, States, LATAs, etc.).
BOC	See Bell Operating Company
Bong	An interactive signal that prompts the originating end user to enter additional information. For example: 1010555 Bong (Enter Destination) Bong (Enter Billing information) Also used to denote a sucharge particularly in the calling card industry.
Broad Band	See Broadband.
Broadband	A high speed data connection to the internet using Cable, Satellite, DSL or ADSl line.
Broadband Phone	A Broadband phone uses the internet and a broadband internet connection to connect you to telephones around the world. This digital system is now well established and can substantial savings on your phone bill. Broadband phone services are available for Business and Residential users.
BTN - Billing Telephone Number	The phone number associated, for billing purposes, with the Working Phone Number.
Bypass	Access an IEC other than the customer's Equal Access carrier by dialing 10+CIC Code.(e.g. Bypass to WorldCom by dialing "1010555"). See Walkthrough, CIC Code
Call Data Record (CDR)	Record of a placed call. A CDR includes the time the call was placed and the duration of the call.
Call Back Service	Telephone service which calls you back after your access their phone system via a custom number or the internet. The call back service calls you back providing you with a dial tone on their service.
Calling Card	A telecommunication credit card with an AuthCode for using a long distance carrier when the customer is away from their home or office (ANI).
Carrier	A telecommunications provider which owns switch equipment.
Carrier Identification Code - CIC	A three digit number used with Feature Groups B and D to access a particular IEC's switched services from a local exchange line. One or more CIC codes are assigned to each carrier. (i.e. there may be multiple CICs per ACNA). See Bypass
Casual Calling	Allow any ANI (including undefined ANIs) to access a given carrier. For example, if the originator is calling from a non-coin phone, they may dial 1010555+destination number and have the call routed through WorldCom and billed to the originating phone
Casual Customer	Any person or organization that dials any CIC Code. (Not necessary to presubscribe to the carrier.)
Centrex	A service that is functionally similar to a customer-premise PBX, but provided by means of equipment located in a Central Office.
Choppiness	Circumstance in which a caller's words are intermittently cut off, creating a situation of gaps in the voice transmission. Choppiness makes it difficult or impossible to have a "normal" conversation.
CIC	See Carrier Identification Code (WorldCom = "555")
Class of Service - COS	A special limitation on what numbers can and cannot be called. International, 809, 809 + Canada, 48 contiguous states, etc.
Clipping	Situation where the system cuts off the first part of the first word in a sentence. (Not to be confused with choppiness -- which is a packet loss).
COCOT	Customer Owned Coin Operated Telephone
Coin Phone	A coin-operated pay phone with restricted access to some services (e.g. International calling). Coin phones have subclasses of Public, Semi Public, and Private.
Collect	A call that is paid for by the receiving/destination phone number. Requires approval/authorization of the person being called.
Common Carrier	A carrier that holds itself out as serving the public (or a segment thereof) indifferently (i.e., without regard to the identity of the customer and without undue discrimination). Common carriers may vary rates based on special considerations and may in fact serve only a small fraction of the general public.
Competitive Local Exchange Carrier (CLEC)	Companies that compete on a selected basis for local exchange service, long-distance, international Internet access, and entertainment (i.e., cable TV).
Computer Telephony Integration (CTI)	Extension of computer-based intelligence and processing over the telephone network to a telephone. CTI lets you interact with computer databases or applications from a telephone. It also enables computer-based applications to access the telephone network. Computer telephony makes computer-based information readily available over the worldwide telephone network from your telephone.
Conference Call	Three or more subscribers on a single phone call simultaneously. Conference calls can have international legs and conference calls can have a moderator to keep things on an even keel!
Contract	A legally-binding agreement between a vendor and a customer to provide Products, Services or Features in a specified quantity and quality, for a specified price, during a specified period of time.
Contract Tariffs	Services and rates based on contracts negotiated with individual customers, but theoretically available to all customers. AT&T has filed several hundred contract tariffs.
CONUS-CONtiguous United States	The 48 contiguous U.S. states. Used primarily to designate the operating range or authorization of a satellite or radio facility.
Country Code	Two or three digit codes used for International calls outside of the North American Numbering Plan area codes. Dial: 011 + country code + city code + local phone number) (e.g. "011 + 91 + 22 + 123- 4567" 91 = India, 22 = Bombay)
Cutover	The exact date/time that a phone number, circuit, etc. is scheduled to be (or was) moved from one implementation (carrier, etc.) to another. (e.g. moving an 800 number from MCI to WorldCom).
Cut-Through Dialing	"10"+CIC+" #" followed by an AuthCode for IntraLATA calls.
DA - Directory Assistance	Phone Number Lookup Service
DAL - Dedicated Access Line	A non-switched circuit from the customer to a carrier.
DDD - Direct Distance Dialing	Any switched telecommunication service (like 1+, 0++, etc.) that allows a call originator to place long distance calls directly to telephones outside the local service area without an operator.
Deactivation	A request to terminate service (or the process of terminating service)
Dedicated Line	A private line leased from a telecommunications carrier.
Default Carrier	Your regular Dial-1 carrier. Call 1-700-555-4141 to find your default carrier.
Dial	To Place A Call On A Switched Network. The term "dial" is obsolete - based on rotary dial phones and electromechanical relay switches (which are nearly non-existent in modern telephone systems.) Touch Tone service recognizes dual tones that are generated as each telephone key is pressed. Where Touch Tone service is not available, telephones and switches electronically "pulse" signals that emulate the older rotary dial telephones. The terms "place" a call or "originate" a call are more accurate than "dial".
Dial Around	Telephone service available from any number via an access number which switches you over to the Dial Around Carrier.
Dial Tone	Ready To Place/Originate A Call. When the off hook indication is received at a central office, a dial tone signal is sent to the originating caller on a switched network to indicate that the switch is ready to accept a number.
Dial-Up	Internet connection via a regular phone line.
Dialer	Equipment that pulses out a standard dial protocol signal.
Digital	A device or method that uses discrete variations in voltage, frequency, amplitude, location, etc. to encode, process, or carry binary (zero or one) signals for sound, video, computer data or other information. For example, a digital clock displays the time as discrete numeric values, rather than angular displacement of analog hands. Digital communications technology generally permits higher speeds of transmission with a lower error rate than can be achieved with analog technology. When analog signals are received and amplified at each repeater station, any noise is also amplified. A digital signal, however, is detected and regenerated (not amplified). Unlike amplification, any noise (less than a valid signal) is eliminated by digital regeneration.
Directory Assistance - DA	An information service whereby operators assist customers in obtaining the telephone number(s) they wish to call.
Design Layout Record (DLR)	Official design of an inter-connection.
DSL	Digital Subscriber Line.
Equal Access	(AT&T Divestiture - 1982 Modified Final Judgement) The provision of one-plus capability to interLATA competitors of AT&T. Customers should be able to reach the carrier of their choice by dialing 1+ the long-distance number. The MFJ and the FCC require local exchange carriers to provide equal access (most central offices now have this capability). Equal Access may also refer to a more generic concept under which the BOCs must provide access services to AT&T's competitors that are equivalent to those provided to AT&T.
Facilities-Based Carrier - FBC	A carrier that uses its own facilities to provide service, in contrast with resellers, that purchase the services of other carriers and then retail the services to customers. (Most facilities-based carriers use the services of other carriers to some extent.)
FCC - Federal Communications Commission	Regulates interstate communications: licenses, rates, tariffs, standards, limitations, etc. Appointed by U.S. President .Web Site = http://www.fcc.gov
Gateway	Device that connects two different kinds of networks and performs the translations required for them to communicate with each other.
Global System for Mobile Communications (GSM)	European protocol used for encoding digital cellular phone transmissions.
H.323	Emerging Internet telephony standard.
High Speed Internet	A broadband connection via cable, satellite, DSL or ADSL. Also an accelerated dial-up connection
IC	Interexchange Carrier - IXC - IEC (IEC is preferred). A company providing long-distance phone service between LECs and LATAs.
IEC - Interexchange Carrier	IC - IXC (IEC is preferred). A company providing long-distance phone service between LECs and LATAs.
IEC Miles	Interexchange Carrier (Long Distance) Miles
Interactive Voice Response System (IVR)	Automated voice response system to guide callers through a series of routine steps. For example, voice mail prompts you to leave a message or the monetary balance on a pre-paid calling card.
Interexchange	Communication between two different LATAs.
InterLATA	Communication between Local Access Transport Areas. 1982 MFJ requires LECs to use an IEC for InterLATA services.
International	Between multiple nations.
International Telecommunications Union (ITU)	Organization in Geneva that evaluates and approves proposed standards for making telecommunications products work together.
Internet Protocol (IP)	Main protocol (i.e., set of rules that formulates the foundation of communication) that controls data flow from one point to the another. It is actually the low-level common denominator of the Internet.
Internet Service Provider (ISP)	Company that offers its customers accesses to the Internet.
Internet Telephony Service Provider (ITSP)	Company that offers its customers the ability to make phone calls over the public Internet.
Interstate	Between multiple states. Interstate communications are regulated by the FCC.
IntraLATA	Communication within a Local Access Transport Area. 1982 MFJ allows LEC to handle these calls without an IEC.
Intrastate	Communication within a single state. Intrastate communications are regulated by each state's PUC.
ISDN (Integrated Services Digital Network)	Phone line service whose technology offers more bandwidth more economically; it is therefore better suited for Internet telephony and video applications. ISDN uses multiple channels for data and voice.
IXC	1) Interexchange Carrier (IEC is preferred). A company providing long-distance phone service between LECs and LATAs. 2) Interexchange Circuit. A circuit that connects PoPs.
IXC Miles	On a Price Quote, the coordinates of Location A and Location B are used to calculate mileage-dependent line charges.
IXC MilesInterexchange Carrier (Long Distance) Miles	On a Price Quote, the coordinates of Location A and Location B are used to calculate mileage-dependent line charges.
Jitter	Difference in arrival time of packets sent at the same time but traveling different routes.
LATA	Local Access Transport Areas (200 in the U.S.). A geographic service area defined in the AT&T Modified Final Judgement. The RBOCs (baby Bells) and GTE are restricted to operations within, but not between, LATAs. Long distance service within a LATA is provided by the LEC. Service between LATAs is provided by an IEC. LATAs are represented by a 3-character code, and there are 164 of them across the country.
Latency	Extent of delay that network components inflict on packets traveling through the network.
LEC	See Local Exchange Carrier
LEC BAN - Billing Account Number	3-digit number appended to the billing phone number used as the LEC customer number. Groups all ANIs for a customer.
LEC Billing	Arrangement whereby the Local Exchange Carrier invoices the customer for some or all telecommunications services.
LEC Card	The billing arrangement which enables the caller to bill calls to an authorized calling card issued by a local exchange carrier.
LEC Charges	Charges that are the responsibility of the local exchange carrier.
Letter Of Agency - LOA	A document that authorizes changing the service provider. (See RespOrg, 800 Portability)
Lightweight Directory Access Protocol (LDAP)	An Internet standard for Internet telephony products that access directory servers.
Local Access	Local Loop. The connection from a subscriber to the Central Office. The portion of a circuit connecting the LEC's CO with the customer's premise equipment across the local network.
Local Access Provider	Any organization that is authorized to provide local access. (May or may not be the LEC.)
Local Area Network (LAN)	Number of computers connected together to form one network.
Local Exchange Carrier - LEC	The local or regional telephone company that owns and operates lines to customer locations and Class 5 Central Office Switches. LECs have connections to other COs, Tandem (Class 4 Toll) offices and may connect directly to IECs like WorldCom, AT&T, MCI, Sprint, etc.
Local Exchange Service	Local phone calls.
Local Loop Provider (LLP)	Company that offers other companies accesses to a telephone switch.
Long Distance Carrier	A company providing long-distance phone service between LECs and LATAs.
Message Toll Service - MTS	Pay-by-the-minute switched long distance services. Includes conventional long distance and measured WATS.
NASC - 800 Number Administration and Service Center	The organization that administers the SMS/800 system for the reservation, registration and administration of all North American 800 numbers for all carriers. (See 800 Portability, RespOrg and SMS/800)
Network Access Points (NAP)	Connection points between different networks.
NPA - Numbering Plan Areas	North American "Area Codes." (3 digits: 2-to-9, 0-or-1, 0-to-9. Middle digit to expand soon)
NPA Area Codes, NXX Exchanges and XXXX Line Numbers	The process for assigning 10-digit (3+3+4) North American telephone numbers
NPA-NXX Routing	Area Code / Exchange Routing. Route calls based on the originating ANI NPA-NXX.
NPA Routing	Area Code Routing. Route calls based on the originating ANI NPA (area code.)
NPA Split	Subdividing an area code, with the creation of a new area code. This is necessary when the number of telephones in an area code (NPA) grows to an excessive number.
NUS	NASC SMS/800 Number Search. SMS application used to find available 800 numbers and reserve them for up to 60 days.
NXX	Exchanges (First 3 digits of a 7-digit phone number). (2-to-9, 0-to-9, 0-to-9) (Digits 4, 5 and 6 in a 10 digit NANP telephone number - NPA-NXX-XXXX).
OCC - Other Common Carrier	Not part of the original AT&T system.
Off Hook	The signal that the telephone receiver has been lifted (activated). Originating off hook activates a dial tone on switched networks. Destination off hook completes a call (and activates minute-by-minute billing for long distance calls).
One Plus - 1+	Customer ability to access the long distance service provider of their choice by first dialing 1, then the long distance number. Equal Access guaranteed by the 1982 AT&T MFJ. 1+ is an outbound service where the calling station pays the charges.
Operator Service Call - OSC	A call that is placed through a human or automated operator (0+).
Operator Service Provider - OSP - OS Provider	The vendor that supplies operator service.
Outbound	Outward Sending - Call Originating - Dialing Out
Packet loss	Loss of parts of the packetized data that comprises the whole communication.
Packetization	Breaking down of data that a computer sends into smaller pieces (known as packets). Each packet has a header that identifies the packet and its destination. The packet travels through routers to its destination computer, which reassembles all the packets that belong together and then sends this reconstituted data to the appropriate program.
Payphone	A public (or private) telephone that accepts coins or encoded credit cards.
Personal Identification Number (PIN)	Personal unique security codes that callers use to access their accounts.
Person-to-Person	Operator assisted phone call - only billed if the specified person is available.
PIC - Primary Interexchange Carrier	The IEC that 1+ calls are routed to. Specified by ANI.
PIC Charges	A LEC charge for changing the PIC. Often paid by the new IEC. If a LEC sends a PIC charge to a customer, the new IEC will typically credit the customer's account.
PIC Freeze	A PIC Freeze prevents the long distance from being switched for the specified ANIs. Useful to prevent slamming, or the unauthorized switching of long distance services.
PIC Request	A request record sent to a LEC asking for an ANI to be activated, deactivated or changed in some way.
PIC Response	A response record sent by a LEC (corresponding to a previous PIC Request) with response code that indicates whether the request was performed. (Some LECs return non-standard PIC Response codes.)
PIN	Personal Identity Number used to provide passwords to calling cards, voip systems, call back services and dial arounds..
Point Of Presence - POP	The physical access location interface between a local exchange carrier and an Interexchange Carrier fiber network. The point to which the telephone company terminates a subscriber's circuit for long distance service or leased line communications.
Point-To-Point	Non-switched, dedicated communication circuit.
Point-to-Point Protocol (PPP)	Protocol to access the Internet using dial-up connections.
POP	See Point Of Presence
POTS	Plain Old Telephone Service
Primary Interexchange Carrier	The long distance company that is automatically accessed when a customer dials 1+.
Private Line	Uses dedicated circuits to connect customer's equipment at both ends of the line. Does not provide any switching capability (unless supported by customer premise equipment). Usually includes two local loops and an IEC circuit.
Provisioning	The process by which a requested (ordered) service is designed, implemented and tracked (providing the subcomponent parts).
Public Switched Telephone Network (PSTN)	The regular, "old-fashioned" telephone network.
PUC - Public Utilities Commission	The agency regulating intrastate phone service.
Rate Element	A recurring fixed charge for IEC or LEC service at the lowest level. A local loop may have multiple rate elements associated with it, which make up the fixed portion of the monthly bill. For example: Local Access, Local Mileage, Entrance facilities, Channel Termination, Interexchange, etc.
Rates and Tariffs	Standards published by AT&T, OCCs,LECs, and IECs that define service availability, cost and provisioning procedures.
Real-Time Transport Protocol (RTP)	Protocol that improves Internet telephone calls by adding special information to the voice data packets to help programs reassemble them more efficiently.
RBOC	Regional Bell Operating Company. Bell operating companies set up after the AT&T divestiture.
Rebiller	See Reseller
Regional Bell Operating Companies - RBOC	One of the seven "Baby Bell" Companies created by the 1982 Modified Final Judgement that specified the terms of the AT&T Divestiture. The seven RHCs include: NYNEX, Bell Atlantic, Bell South, Southwestern Bell, U.S. West, Pacific Telesis, and Ameritech. "RBOC" is sometimes used informally to refer to the Regional Holding Companies defined in the 1982 MFJ. (See Bell Operating Companies - There are 19 BOCs).
Regulators	FCC, PUC, Federal Courts (e.g. MFJ), etc.
Reseller - Also known as Rebiller	A long-distance carrier (IEC) that does not own a network, but leases bulk capacity and resells portions of it at a higher rate.
Residential Customer	An individual (non-business) telephone system subscriber.
Responsible Organization - R/O - Resporg	With 800 Portability, the Number Administration Service Center (NASC) allows the RespOrg to make changes such as carrier, termination, 800 call routing (by time of day, location.) A Letter Of Agency (LOA) must be on file to change the RespOrg for each customer/account.
Router	Switching device that that directs traffic through the Internet.
Satellite Internet	A broadband internet connection via satellite.
Secure Socket Layer (SSL)	Encrypted communications path between two computers. Theoretically protects customer information.
Serial Line Interface Protocol (SLIP)	Protocol to access the Internet using dial-up connections.
Slam	An end user that is PICed without their permission. An RBOC Slam Fee must be paid for each slam.
SMS	Service Management System
SMS Customer Record	All information related to one 800 number, effective date and time, etc.
Speed Dialing	A service to abbreviate and accelerate frequently dialed numbers.
State Tax	A collection of tax types that each state is allowed to charge. Tax jurisdiction (which state can charge tax for a call) is based on the two-out-of-three rule: where it originates, where it terminates, where it is being billed to - if two match, that state can charge the tax.
Surcharge	An additional charge on top of a base rate for a specified reason.
Switch	A device (like a DMS-250 or a PBX) that responds to originator signals and dynamically connects the caller to the desired communication destination.
Switched Access	Nondedicated local access between the customer's premise and the serving wire center which is interconnected to the company's point-of-presence for origination or termination of service.
Switched Access Service	A class of LEC services that provides the link from the customer's premise to the IEC PoP for switched circuits.
Switched Resellers	Resellers that utilize their own switching hardware (and sometimes their own lines) and the lines of other IXCs to provide long-distance service to its subscribers. They provide their own billing and service.
Switched Services	All dial up long-distance services including conventional residential and WATS (most have incremental use charges). (See Message Toll Service)
Switching Fee	A per-line fee (usually around 5$) imposed by the LEC to reprogram their switching system to change your default carrier. Subscribers must usually pay this fee when switching to a reseller.
Switchless Reseller	A reseller of long-distance services that does not utilize any of its own lines, or (switching) equipment. All actual service and equipment is handled by the IXC. Billing is usually done, by the reseller themselves, to the customer.
System Management Network Protocol (SMNP)	Piece of equipment's ability to be remotely monitored.
T1/DS-1	(Facility) The equivalent of 24 multiplexed voice grade channels. 1.544 million bits per second (1.5Mbps)
T2/DS-2	(Facility) The equivalent of 4 multiplexed T1 channels. 6.312 million bits per second (6.3Mbps)
T3/DS-3	(Facility) The equivalent of 28 multiplexed T1 channels. 44.736 million bits per second (45Mbps)
T4/DS-4	(Facility) The equivalent of 6 multiplexed T3 channels. 274.176 million bits per second (274Mbps)
Tariff	A public document filed with the FCC or a PUC that outlines services and rates. Usually, all customers are offered the same rate for a specific service, based on published constraints.
TDD	Telecommunications Device for the Deaf
Telco - Telephone Company	The local or regional telephone company that owns and operates lines to customer locations and Class 5 Central Office Switches. Telcos have connections to other COs, Tandem (Class 4 Toll) offices and may connect directly to IECs like WorldCom, AT&T, MCI, Sprint, LDDS, etc.
Termination gateway	The computer equipment configured with certain hardware and software, which provides the electronic "bridge" from an IP network to the PSTN to connect to the destination telephone.
Third Party Billing	Use of an outside service bureau for bill processing such as: call rating, customer invoicing, collections, etc.
Time of Day Routing	Route calls based on the time the call originates. (e.g. direct morning calls to East Coast operators and afternoon calls to West Coast operators, etc.). SMS/800 supports 15 minute time intervals.
Toll	A rated call (Contrast CDR - unrated call detail record). Tolls appear on the Invoice Detail.
Toll Call	A call with incremental use (minute-by-minute) charges. (Often through a Class 4 Toll Office).
Toll Free Number	An 800 or similar number where the recipient pays the cost of the incoming call.
Toll Fraud	A crime in which a "hacker" obtains telecommunication services by: breaching computer security, using or selling stolen long-distance credit-card codes, or, accessing a PBX and using its communication facilities illegally. Toll Fraud is estimated to cost U.S. companies $1.2 billion/year.
Transmission Control Protocol (TCP)	More reliable protocol for monitoring the control of data -- because it checks data at the destination to ensure that all packets are received. If any are missing, TCP resends them.
Trunk, trunk group	Number of phone lines grouped together going to the same place.
Two Out Of Three Rule	When determining state tax jurisdiction, there are three locations to consider: originating station, destination station, and the location that the bill is sent to. If two out of three are the same, then that state receives the tax.
Universal Asynchronous Receiver/Transmitter (UART)	Chip that controls the serial port in a computer.
User Datagram Protocol (UDP)	A protocol similar to TCP; however, it does not check data at the receiving end to ensure that all the packets have arrived, and doesn't re-send missing data.
Value Added Reseller (VAR)	Company offering services other than the core service. For example, a company who sells computers and offers training, service, and on-going maintenance is considered a VAR.
Vanity Number	A specific 800 or 888 number (may spell something).
Verified Account Codes	See Account Codes. A finite list of carrier-verified, predefined Account Codes.
Video Conference	A conference call with video feeds so the parties can see each other or can see educational or discussion material.
Vocoder	Compresses a digital signal and then decompresses it. (Also known as coder.)
Voice Mail	An automatic answering service with the ability to record a message. Unlike simple answering machines, Voice mail uses a programmable computer system with options such as temporary call routing, monitoring and reporting, etc.
Voice Mail Box	The assignment of one user/number on a voice mail system.
VOIP	Voice over IP. Vioce transmission using the internet to digitally transmit voice signal. VOIP is used from pc to pc, from pc to phone and to power Broadband phones. Also for conference calling and video conferencing.
WATS - Wide Area Telephone Service	Flat rate, or special rate pay-by-the-minute (measured) billing for a specified calling area. May be outbound or inbound (e.g. 800).
Wide Area Network (WAN)	Number of computers connected together to form one network over several locations. Could be made up of several LANS all connected together across the world for example.
Wireless	Radio waves, cellular, satellite, microwave, etc.
WNP	Wireless Number Portability.
WTN	Working Telephone Number.
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