T.120
The T.120, an ITU-T standard, is made up of a suite of communication and application protocols. T.120 protocols are designed for multipoint Data Conferencing and real time communication, including multilayer protocols which considerably enhance multimedia, MCU and codec control capabilities. Depending on the type of T.120 implementations, the resulting product can make connections, transmit and receive data and collaborate using compatible data conferencing features, such as program sharing, whiteboard conferencing and file transfer.
Standard Organization: ITU-T
Reference Document: T.120

T.30
The T.30, an ITU-T standard, describes the overall procedure for establishing and managing communication between two fax machines.
Standard Organization: ITU-T
Reference Document: T.30

T.38
The T.38, an ITU-T standard, defines procedures for real-time Group 3 facsimile communication over IP networks.
Standard Organization: ITU-T
Reference Document: T.38

TABS: Telemetry Asynchronous Block Serial
Telemetry Asynchronous Block Serial (TABS) is an AT&T polled point-to-point or multipoint communication protocol that supports moderate data transfer rates over intra-office wire pairs.
Standard Organization: AT&T

TACACS: Terminal Access Controller Access Control System
The Terminal Access Controller Access Control System (TACACS) provides access control for routers, network access servers and other networked computing devices via one or more centralized servers. TACACS provides separate authentication, authorization and accounting services. There are three versions of TACACS and the third version is called TACACS+, which is not compatible with previous versions.
Standard Organization: Cisco

TACACS+: Terminal Access Controller Access Control System (version 3)
Terminal Access Controller Access Control System (version 3), also known as TACACS+, provides access control for routers, network access servers and other networked computing devices via one or more centralized servers. TACACS provides separate authentication, authorization and accounting services. TACACS+ is not compatible with previous versions of TACACS.
Standard Organization: Cisco

TALI: Tekelec's Transport Adapter Layer Interface
Tekelec's Transport Adapter Layer Interface (TALI), a protocol in the SIGTRAN suite, is the interface of a Signaling Gateway, which provides interworking between the Switched Circuit Network (SCN) and an IP network. Since the Gateway is the central point of signaling information, not only does it provide transportation of signaling from one network to another, but can also provide additional functions such as protocol translation, security screening, routing information and seamless access to Intelligent Network (IN) services on both networks.
Standard Organization: IETF
Reference Document: RFC 3094

TAP: Telocator Alphanumeric Protocol
Telocator Alphanumeric Protocol (TAP) is a simple protocol dedicated to the forwarding of alphanumeric pages. Although the features and capabilities of TAP are in TDP, the TAP protocol may co-exist with TDP. The TAP protocol may be utilized to forward binary data to RF-linked computers if input is formatted and processed.

TARP: TID Address Resolution Protocol
TID Address Resolution Protocol (TARP) is a protocol defined in Telcordia (a.k.a Bellcore) GR-253 standard document for SONET and used in OSS to resolve a TL1 TID to a CLNP address (NSAP). Many legacy SONET systems still use TARP to translate Target Identifier of a SONET node.
Standard Organization: Telcordia

TBOS: Telemetry Byte Oriented Serial Protocol
Telemetry Byte Oriented Serial(TBOS) protocol is an open standard for network management, originally developed by Bellcore for AT&T. TBOS transmits alarm, status, and control points between NE and OSS. TBOS defines one physical interface for direct connection between the telemetry equipment and the monitored equipment.
Standard Organization: AT&T

TCAP: Transaction Capabilities Application Part
Transaction Capabilities Application Part (TCAP), a protocol in the SS7 protocol suite, enables the deployment of advanced intelligent network services by supporting non-circuit-related information exchange between signaling points, using the Signaling Connection Control Part (SCCP) connectionless service. TCAP also supports remote controlability to invoke features in another remote network switch.
Standard Organization: ITU-T
Reference Document: Q.773

TCP Port Numbers
TCP Port Numbers are designed to distinguish multiple applications running on a single device with one IP address from one another. In the TCP header, there are "SourcePort" and "DestinationPort" fields which are used to indicate the message sending process and receiving process identities defined. The combination of the IP address and the port number is called "socket".
Standard Organization: IANA

TCP/IP
The TCP/IP protocol suite establishes the technical foundation of the Internet. Development of the TCP/IP started as DOD projects. Now, most protocols in the suite are developed by the Internet Engineering Task Force (IETF) under the Internet Architecture Board (IAB), an organization initially sponsored by the US government and now an open and autonomous organization. The IAB provides the coordination for the R&D underlying the TCP/IP protocols and guides the evolution of the Internet. The TCP/IP protocols are well-documented in the Request For Comments (RFC), which are drafted, discussed, circulated and approved by the IETF committees. All documents are open and free and can be found online in the IETF site listed in the reference.
Standard Organization: IETF

TCP/IP Four Layers Architecture Model
TCP/IP architecture does not exactly follow the OSI model. Unfortunately, there is no universal agreement regarding how to describe TCP/IP with a layered model. It is generally agreed that TCP/IP has fewer levels (from three to five layers) than the seven layers of the OSI model. We adopt a four layers model for the TCP/IP architecture.

TCP: Transmission Control Protocol
Transmission Control Protocol (TCP) is the transport layer protocol in the TCP/IP suite which provides a reliable stream delivery and virtual connection service to applications through the use of sequenced acknowledgment, with retransmission of packets when necessary. Along with the Internet Protocol (IP), TCP represents the heart of the Internet protocols.
Standard Organization: IETF
Reference Document: RFC 793

TCS: Telephony Control Protocol Specification
The Telephony Control Protocol Specification (TCS) is a protocol in the Bluetooth protocol stack that defines ways to send audio calls between Bluetooth devices. It also controls the device mobility management procedures. It can be used to create a three-in-one phone:
1) On the move, a mobile phone connected to a cellular network;
2) At home, a cordless phone connected to a PSTN via a gateway or base station;
3) At the office, an intercom.
Standard Organization: IEEE
Reference Document: 802.15.1

TDP: Tag Distribution Protocol
Tag Distribution Protocol (TDP), a two-party protocol defined by Cisco originally, runs over a connection-oriented transport layer with guaranteed sequential delivery. The MPLS protocol, based on the TDP, has gained popularity among service providers as the protocol for next generation multiple service networks.
Standard Organization: Cisco

TDP: Telocator Data Protocol
Telocator Data Protocol (TDP) is a suite of protocols used for sending messages from a computer, through a paging system, to a mobile receiving computer. Together, these protocols define the flow of messages from input devices through several processing steps until the entire message is received by an RF-linked computer. The set is compromised of several protocols, including TME, TRT, and TMC.

TELNET: Terminal Emulation Protocol in a TCP/IP environment
TELNET is the terminal emulation protocol in a TCP/IP environment for the remote access of a terminal (client) to a server. TELNET uses the TCP as the transport protocol to establish connection between server and client. After connecting, TELNET server and client enter a phase of option negotiation that determines the options that each side can support for the connection. Each connected system can negotiate new options or renegotiate old options at any time. In general, each end of the TELNET connection attempts to implement all options that maximize performance for the systems involved.
Standard Organization: IETF
Reference Document: RFC 854

TFTP: Trivial File Transfer Protocol
Trivial File Transfer Protocol (TFTP) is a simple protocol to transfer files. It has been implemented on top of the User Datagram Protocol (UDP) using port number 69. TFTP is designed to be small and easy to implement and, therefore, lacks most of the features of a regular FTP. TFTP only reads and writes files (or mail) from/to a remote server. It cannot list directories and currently has no provisions for user authentication.
Standard Organization: IETF
Reference Document: RFC 1350

THDR: Transport Layer Header
Transport Layer Header (THDR), a protocol in the IBM SNA suite, is used by RTP endpoints to provide correct processing of the packet.
Standard Organization: IBM

TIFF: Tagged Image File Format
Tagged Image File Format (TIFF) is a file format mainly for storing images, including photographs and line art. Originally created by the company Aldus, now part of Adobe Systems for use with PostScript printing, TIFF is a popular format for high color-depth images, along with JPEG and PNG. TIFF format is widely supported by image-manipulation applications such as Photoshop by Adobe, GIMP, and Paint Shop Pro by Jasc, by desktop publishing and page layout applications, such as QuarkXPress and Adobe InDesign, and by scanning, faxing, word processing, optical character recognition, and other applications.
Standard Organization: Adobe

Time Protocol
Time Protocol allows time clients to obtain the current time-of-day within one-second resolution from Time servers.
Standard Organization: IETF
Reference Document: RFC 868

Timeplex BRE: Bridge Relay Encapsulation
Bridge Relay Encapsulation (BRE) is a proprietary Ascom Timeplex protocol that extends bridging across WAN links by means of encapsulation. The BRE version 2 (BRE2) sits directly on the link layer protocol, requires less configuration and provides its own routing protocol.
Standard Organization: Ascom Timeplex

TKIP: Temporal Key Integrity Protocol
Temporal Key Integrity Protocol (TKIP) is part of the IEEE 802.11i encryption standard for wireless LANs security. TKIP utilizes RC4 stream cippher with 128 bit key for encryption and 64 bit key for authentication. TKIP is the next generation of WEP (Wired Equivalency Protocol). TKIP provides per-packet key mixing, a message integrity check and a re-keying mechanism, thus fixing the flaws of WEP.
Standard Organization: IEEE
Reference Document: IEEE 802.11i

TLAP: TokenTalk Link Access Protocol
TokenTalk Link Access Protocol (TLAP) is a link-access protocol used in an AppleTalk network. TLAP is built on top of the standard Token Ring data-link layer.
Standard Organization: Apple

TLS: Transport Layer Security Protocol
Transport Layer Security (TLS) protocol, based on SSL developed by Netscape, provides privacy and data integrity between two communicating applications. TLS is used extensively by web browsers to provide secure connections for transferring credit cards numbers and other sensitive data. Though SSL was superseeded to TLS by IETF, but the SSL name has gained enough popularity and people still call the protocol SSL or SST/TLS. The protocol is composed of two layers: the TLS Record Protocol and the TLS Handshake Protocol. At the lowest level, layered on top of some reliable transport protocol (TCP) is the TLS Record Protocol.
Standard Organization: IETF
Reference Document: RFC 2246

TMC: Telocator Mobile Computer Protocol
Telocator Mobile Computer Protocol (TMC) is the protocol that operates between the Radio Frequency (RF) receiver and the mobile computer, which is the ultimate recipient of data sent from the Message Entry Device (MED).

TME: Telocator Message Entry Protocol
Telocator Message Entry Protocol (TME) defines the protocol operating between the Message Entry Device (MED) and Paging Message Processor (PMP).

Token Ring
Token Ring is a LAN protocol, defined in IEEE 802.5, where all stations are connected in a ring and each station can directly hear transmissions only from its immediate neighbor. Permission to transmit is granted by a message (token) that circulates around the ring.
Standard Organization: IEEE
Reference Document: IEEE 802.5

TOP: Technical Office Protocol
Technical Office Protocol (TOP) is an applications layer network application and protocol stack for office automation developed by Boeing. TOP is very similar to MAP except at the lowest levels, where it uses Ethernet (IEEE 802.3) rather than Token Bus (IEEE 802.4).
Standard Organization: Boeing

Toshiba FANP: Flow Attribute Notification Protocol
Flow Attribute Notification Protocol is a protocol between neighbor modes which manages cut-through packet forwarding functionalities. In cut-through packet forwarding, a router does not perform conventional IP packet processing for received packets. FANP indicates mapping information between a datalink connection and a packet flow to the neighbor node. It helps a pair of nodes manage mapping information.
Standard Organization: Toshiba

TP: ISO Transport Protocol
The OSI Transport layer protocol (ISO-TP or TP) manages end-to-end control and error checking to ensure complete data transfer. It performs transport address to network address mapping, makes multiplexing and splitting of transport connections, also provides functions such as Sequencing, Flow Control and Error detection and recover. Five transport layer protocols exist in the OSI suite, ranging from Transport Protocol Class 0 through Transport Protocol Class 4 (TP0, TP1, TP2, TP3 & TP4). The protocols increase in complexity from 0-4. TP0-3 work only with connection-oriented communications, in which a session connection must be established before any data is sent; TP4 also works with both connection-oriented and connectionless communications.
Standard Organization: ISO
Reference Document: ISO Document 8073

TP0: ISO Transport Protocol Class 0
Transport Protocol Class 0 (TP0), one of the five transport layer protocols existing in the OSI suite, performs segmentation (fragmentation) and reassembly functions. TP0 discerns the size of the smallest maximum protocol data unit (PDU) supported by any of the underlying networks, and segments the packets accordingly. The packet segments are reassembled at the receiver.
Standard Organization: ISO
Reference Document: ISO Document 8073

TP1: ISO Transport Protocol Class 1
Transport Protocol Class 1 (TP1), one of the five transport layer protocols existing in the OSI suite, performs segmentation (fragmentation) and reassembly, plus error recovery. TP1 sequences protocol data units (PDUs) and will retransmit PDUs or re-initiate the connection if an excessive number of PDUs are unacknowledged.
Standard Organization: ISO
Reference Document: ISO Document 8073

TP2: ISO Transport Protocol Class 2
Transport Protocol Class 2 (TP2), one of the five transport layer protocols existing in the OSI suite, performs segmentation and reassembly, as well as multiplexing and demultiplexing of data streams over a single virtual circuit.
Standard Organization: ISO
Reference Document: ISO Document 8073

TP3: ISO Transport Protocol Class 3
Transport Protocol Class 3 (TP3), one of the five transport layer protocols existing in the OSI suite, offers error recovery, segmentation and reassembly, and multiplexing and demultiplexing of data streams over a single virtual circuit. TP3 also sequences PDUs and retransmits them or re-initiates the connection if an excessive number is unacknowledged.
Standard Organization: ISO
Reference Document: ISO Document 8073

TP4: ISO Transport Protocol Class 4
Transport Protocol Class 4 (TP4), one of the five transport layer protocols existing in the OSI suite, offers error recovery, performs segmentation and reassembly, and supplies multiplexing and demultiplexing of data streams over a single virtual circuit. TP4 sequences PDUs and retransmits them or re-initiates the connection if an excessive number are unacknowledged. TP4 provides reliable transport service and functions with either connection-oriented or connectionless network service. TP4 is the most commonly used of all the OSI transport protocols, which is similar to the Transmission Control Protocol (TCP) in the TCP/IP suite.
Standard Organization: ISO
Reference Document: ISO Document 8073

TRIP: Telephony Routing over IP
Telephony Routing over IP (TRIP) is a policy-driven inter-administrative domain protocol for advertising the reachability of telephony destinations between location servers and for advertising attributes of the routes to those destinations. TRIP's operation is independent of any signaling protocol; hence TRIP can serve as the telephony routing protocol for any signaling protocol.
Standard Organization: IETF
Reference Document: RFC 3219

TRISL: Token Ring Inter-Switch Link
Token Ring Inter-Switch Link(TRISL) is a Cisco protocol for interconnecting multiple routers and switches and maintaining VLAN information as traffic goes between routers and switches. The TRISL feature provides a method to transport native Token Ring frames from multiple VLANs across a 100-MB Fast Ethernet link.
Standard Organization: Cisco

TUA: TCAP-User Adaptation Layer
TCAP-User Adaptation Layer (TUA) TUA is an SS7 Signalling User Adaptation Layer for providing TCAP-User signalling over SCTP. TUA is intended to be used on a Provider/User basis where TCAP resides on a Signalling Gateway (SG) and TCAP Users reside on an Application Server (AS). TUA is an integral part of the OpenSS7 SIGTRAN stack.
Standard Organization: IETF

TUD: Trunk up-down
Trunk up-down(TUD) is a protocol used in ATM networks that monitors trunks and detects when one goes down or comes up. ATM switches send regular test messages from each trunk port to test trunk line quality. If a trunk misses a given number of these messages, TUD declares the trunk down. When a trunk comes back up, TUD recognizes that the trunk is up, declares the trunk up, and returns it to service.

TULIP: TCP and UDP over Lightweight IP
TCP and UDP over Lightweight IP (TULIP) is a protocol for running TCP and UDP applications over ATM, in which only the IP protocol field is carried in each packet, and everything else being bound at call set-up time. In this case, the implicit binding is between the IP entities in each host. Since there is no further routing problem once the binding is established, since AAL5 can indicate packet size, since fragmentation cannot occur, and since ATM signaling will handle exception conditions, the absence of all other IP header fields and of ICMP should not be an issue. Entry to TULIP mode would occur as the last stage in SVC signaling, by a simple extension to the encapsulation negotiation. TULIP changes nothing in the abstract architecture of the IP model, since each host or router still has an IP address which is resolved to an ATM address. It simply uses the point-to-point property of VCs to allow the elimination of some per-packet overhead. The use of TULIP could, in principle, be negotiated on a per-SVC basis or configured on a per-PVC basis.
Standard Organization: IETF
Reference Document: RFC 1932

TUNIC: TCP and UDP over Nonexistent IP Connection
TCP and UDP over Nonexistent IP Connection(TUNIC) is a protocol for running TCP and UPD applications over ATM. In this case, no network-layer information is carried in each packet and everything is bound at virtual circuit set-up time. The implicit binding is between two applications using either TCP or UDP directly over AAL5 on a dedicated VC. If this can be achieved, the IP protocol field has no useful dynamic function. However, in order to achieve binding between two applications, the use of a well-known port number in classical IP or in TULIP mode may be necessary during a call set-up.
Standard Organization: IETF
Reference Document: RFC 1932

TUP: Telephone User Part
The Telephone User Part (TUP) provides the signaling backbone between switching elements for basic call establishment, supervision, and release of circuit switched network connections for telecommunications services. TUP supports analog and digital circuits, and limited call management signaling.
Standard Organization: ITU-T
Reference Document: Q.763