Glossary of Telecom Terms : T

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T-1 Circuit
A digital circuit that uses the DS-1 signaling format to transmit information over the telephone network at 1.544 megabits per second. Can carry up to 24 uncompressed voice channels.


The connection of networks or circuits in series; that is, the connection of the output of one circuit to the input of another. See Tandem Switch.


Tandem Point
An intermediate location in a tandem architecture. The tandem point passes a call to the next destination.


Tandem Switch
Tandem is a telephony term meaning "to connect in series." Thus, a tandem switch connects one trunk to another. A tandem switch is an intermediate switch or connection between an originating telephone call or location and the final destination of the call.


Tandem Switching Provider (TSP)
Any Interexchange Carrier, end user, or other access provider that provides tandem switching functions for switched transport services.


Tandem Switched Transport
Consists of circuits dedicated to the use of a single customer from the serving wire center to the tandem switch and circuits used in common by multiple customers from the tandem switches to an end office.


Tandem Transit Service
Enables end users of a CLEC to originate intraLATA calls destined for an end user of a third local exchange carrier.


A statement by a communications company filed with the FCC that sets forth services offered, and rates, terms, and conditions for those services.


See Transaction Capabilities Application Port.


See Transmission Control Protocol/Internet Protocol.


See Transaction Code Status Indicators.


Technically Feasible Points
Points at which it is technically or operationally feasible to interconnect with the Verizon network without threatening the reliability or security of the existing network.


Telcordia Technologies
Formerly known as Bellcore, this corporation conducts research and development projects including development of new telecommunications services. Telcordia also provides centralized technical and management services for the Regional Holding Companies. In addition, Telcordia provides generic requirements for the telecommunications industry for products, services, and technologies.


As defined in the Telecommunications Act of 1996, transmission between or among points specified by the user, of information of the user's choosing, without change in the form or content of the information as sent and received. Any transmission, emission, or reception of signs, signals, writings, images, and sounds or intelligence by wire, radio, optical, or other electromagnetic systems.


Telecommunications Act of 1996
Public Law 104-104, enacted February 8, 1996, provided comprehensive reform of the 1934 Communications Act. The Act was designed to foster competition among local telephone, long distance telephone, cable and other communications companies.


Telephone Number Assignment Inquiry
A Verizon Wholesale local pre-order transaction that allows the CLEC to reserve an end user telephone number(s).


Telecommunications Resellers Association (TRA)
An organization representing the interests of more than 200 companies involved in the resale of telecommunications services.


Telecommunications Service
As defined in the Telecommunications Act of 1996, the offering of telecommunications for a fee directly to the public, or to such classes of users as to be effectively available directly to the public, regardless of the facilities used to transmit the telecommunications services.


Three-Tone Slope
The loss at 404 Hz and 2804 Hz relative to the loss at 1004 Hz.


A measure of the overall efficiency, quality and performance of a communications link and its software/protocols.


Time Call Hour Indicator
The hour at which the call was placed.


Time Call Minute Indicator
The minute within the hour at which the call was placed.


Token Ring
A local area network architecture that connects stations by using a token (special data packet) passing access method to allow a token to be passed from node to node on the ring.


Toll Call
Call made within a Regional Calling Area to exchanges outside the local calling area. Toll calls are individually detailed on a bill.


See Type of Service.


TR008 Line Port
A Verizon Wholesale UNE service that provides integrated access to Verizon's digital switch, allowing analog-switched services to be provisioned according to Telcordia TR008 standards.


See Telecommunications Resellers Association.



  1. Messages sent and received over a communications channel.
  2. Quantitative measurement of the total messages and their length, expressed in hundred call seconds (CCS) or other units.

Transaction Capabilities Application Port (TCAP)
Functions that control non-circuit related information switched between two or more signaling nodes.


Transaction Capability Application Port (TCAP) Services Forecast
A list of intended TCAP services that identifies serving node and the Verizon Local Access and Transport Area (LATA) for each of the next three years.


Transaction Code Status Indicators (TCSI)
The "intelligence" codes that are used by carrier customers and Local Service Providers to exchange Primary Interexchange Carrier (PIC) and end user information via the industry standard Customer Account Record Exchange (CARE).


Transmission Control Protocol/Internet Protocol (TCP/IP)
A widely used network protocol that supports communication across interconnected networks; and between computers with diverse hardware architectures and various operating systems.


Transmission Level Point (TLP)
A point in a transmission system at which the ratio, usually expressed in decibels, of the power of a test signal at that point to the power of the test signal at a reference point is specified.


Transmission Repeater
Loop enhancement equipment that amplifies and equalizes voice grade signals.


Trigger Mechanism
The elements within a service provider's network that allows switches to determine that a particular call might be routed to a ported number, and to attempt to obtain additional routing information.


Trouble Administration
The process of reporting and tracking problems (troubles) on telephone numbers or circuits.


Trouble Ticket
A record used for reporting and managing the resolution of network or circuit outages.


Trouble Ticket Modify (TTMOD)
The transaction a CLEC or Reseller uses to add, change or delete a previously created Verizon trouble ticket (for example, for rescheduling repair activities). A CLEC or Reseller may submit a modification for any open trouble ticket, but not for a closed trouble ticket.


A communications path connecting two switching systems in a network, used to establish an end-to-end connection.


Trunk Group
A set of trunks that are traffic engineered as a unit in order to establish connections between switching systems in which all of the communications paths are interchangeable.


A central office switch connection that has been programmed to treat the circuit as connecting to another switching entity (for example, another carrier's network). Trunk-side connections offer transmission and signaling features that are appropriate for connecting switching entities.


Twisted Pair (TP)
Cable consisting of two 18 to 24 AWG (American Wire Gauge) solid copper strands twisted around each other. The twisting provides a measure of protection from electromagnetic and radio-frequency interference.


Two Binary, One Quaternary (2B1Q)
A line code used for BRI and Centrex BRI where each two bits of the binary data stream are combined into a single four-level pulse amplitude modulation signal.


Two-Way Wireless Mobile Telecommunications Service Provider
A CMRS Provider of telephone exchange and exchange access services. There are the following types:

  1. Type 2T--A pre-251/252 interconnection between a CMRS Provider and an access tandem. This interconnection was used exclusively for the purpose of routing equal access traffic from the CMRS Provider to the ICs.
  2. Type 2B--A pre-251/252 interconnection between a CMRS Provider and an end office giving access only to the end office of interconnection and its pair gain devices. Ancillary services such as directory assistance, 0+/0-, etc., were not part of the M/L calling scope of this interconnection.
  3. Type 1--A pre-251/252 interconnection between a CMRS Provider and an end office for the purpose of originating and terminating traffic or for access to end user services such as directory assistance, operator services, 9-1-1, etc.
  4. Type 2A--A pre-251/252 interconnection between a CMRS Provider and an access tandem for the purpose of originating and terminating traffic to the end offices subtending the access tandem. Ancillary services such as directory assistance, 0+/0-, etc., were not part of the M/L calling scope of this interconnection.

Two-Wire Links
A two-wire link (or loop) is available for the transmission of analog or digital signals between Verizon's central office and the network interface device at the end user's premises.


Type of Service
A four-character field on a Local Service Request that identifies the End User's account type as business, residential or government; also identifies the product, class and characterization of the product being ordered.



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