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S point

In ISDN telephony, the service access point between TE1 and NT2 equipment. See also NT2, SAP, TE1.

SAP

Service Access Point; in the OSI layering model, the point at which a layer provides services to the layer directly above it. A unique Service Access Point Identifier (SAPI) is associated with each SAP. See also ISDN, OSI, SAPI.

SAP

Service Access Point; a user interface by which an application can access an SS7 service. A SAP exists for every application using the SS7 service.

SAPI

Service Access Point Identifier; in the OSI layering model, a unique identifier for a service access point (SAP). See also ISDN, OSI, SAP.

SCCP

Signaling Connection Control Part; an SS7 protocol that provides both connection-oriented and connectionless data transfer over an SS7 network. It extends the service provided by the SS7 MTP layers by adding extended addressing capabilities and multiple classes of service. The SCCP addressing capabilities allow a message to be addressed to an individual application or database within a signaling point. See also SS7.

SCP

Service Control Point; an SS7 signaling point containing a centralized database or enhanced service application. For example, 800 number translation databases, or the HLR (home location register) and VLR (visitor location register) databases in wireless networks.

SD recognition

See speaker-dependent speech recognition.

SEC8K

Secondary reference clock. The SEC8K clock typically drives the MC1_8K (8KREF) clock in an MC1 system, or is used as the backup reference clock on an MVIP-90 bus. See also clock master, clock slave.

secondary [clock] master

Backup to the primary clock master in an MC1 system. Drives whichever clocks the primary master is not driving (left or right). See also clock master, left clocks, MC1, primary [clock] master, right clocks.

send queue

A NaturalFax document queue structure for document files to be sent from one fax terminal to another. A send queue can only be used to send a queue of documents (the NaturalFax application is acting as the transmitter). It cannot be used to receive document files when the NaturalFax application is acting as the receiver. Only files that already exist can be added to a send queue. A unique file can be placed in multiple send queues simultaneously. See also document queue, receive queue.

service

In CT Access, a group of logically related telephony functions. A service may be implemented on multiple hardware boards. No matter what hardware is providing the functionality, all services with the same functionality have a standard API. This enables device-independent programming.

service API

In CT Access, a set of function calls, including arguments and managed parameters, return values, and asynchronous events that define the work that is done by the service.

service ID

16-bit numeric value embedded in all commands, errors, and event messages of a CT Access service.

service managers

Service managers implement CT Access services, communicate with the dispatcher, and adhere to CT Access standards. They are implemented as dynamic link libraries (DLLs) in Windows NT and as shared libraries in UNIX, and are linked to the application. See also dispatcher.

service SPI

In CT Access, a group of lower-level functions corresponding to the service API which converts the service API calls into messages suitable for transmission to the service implementation.

SI recognition

See speaker-independent speech recognition.

Signaling Point

A node in the SS7 network uniquely identified by a point code. See also point code.

signaling

Information relayed between parties that is related to the process of a call (e.g., the status of the line, call progress and control information, etc.) rather than the content of the call (e.g., data or voice information).

Signaling Link Set

A group of parallel signaling links carrying SS7 traffic and terminating on the same pair of signaling points. Typically all traffic between two signaling points is load-shared between all available links in a link set.

simplex

A circuit which carries information in only one direction. See also full-duplex, half-duplex.

SIT

Special Information Tone; a series of three tones followed by an informational voice message indicating a network error such as congestion or an unknown telephone number.

slave

Bus clock slave; derives the clock signal from the bus clock, which is driven by the bus clock master. See also clock slave, clock master.

SLIC

Subscriber Line Interface Circuit; in digital telephony, the circuit which performs some or all of the interface functions at the central office.

snapshot

In the TX environment, a dump file, usually named cpsnap.dmp, that a user can create to assist in the diagnosis of internal CP operations. The snapshot file is an image of every byte of memory on the CP at the time of snapshot.

socket

A unique identifier (for a destination) at the network layer that combines a port and an IP address. See also IP address, network layer, port.

solicited event

An event that occurs as a consequence of some function call.

span line

A T1 line. Also known as a T1 trunk, or as a span.

speaker-dependent speech recognition

Recognizes the utterances of users who have provided training data so that the recognizer associates words with their specific pronunciations.

speaker-independent speech recognition

Recognition type which has the quality of being able to recognize the same utterances spoken by different speakers, without requiring training.

special information tone

See SIT.

speech recognizer

The software and hardware components necessary to perform speech recognition: a set of C API functions, a set of data structures, a set of parameters, and a DSP chip.

spoofing

Simulating a communications protocol by interjecting a program into a normal sequence of processes for the purpose of adding some useful function. In fax technology, spoofing "fools" the destination fax machines into believing they are receiving image data within the T.30 fax timeout limits.

SRAM

Static Random Access Memory; RAM that retains its data without the refreshing required by DRAM. SRAM offers faster memory access time and is more expensive than DRAM. See also DRAM.

SS5

Signaling System 5; a trunk protocol that uses in-band compelled signal frequency tones to perform live signaling, and in-band MF tones to perform register signaling, for T1 and E1 trunks.

SS7

Signaling System 7; an out-of-band signaling system that provides fast call setup (using circuit-switched connections) and transaction capabilities for remote database interactions.

SSP

Service Switching Point; an SS7 signaling point which originates and terminates signaling messages and provides some circuit switching capability. A central office switch is an example of an SSP.

standard parameters

In CT Access, a defined set of parameters that all conforming services must expose.

standard switching compliant

See MVIP Standard Switching Compliant device.

Static Random Access Memory

See SRAM.

store-and-forward

An application that receives data, such as a fax image or voice data, stores it temporarily, and forwards it to its final destination. Typical fax store-and-forward applications include "never busy fax" applications, and applications which transmit a fax image to a remote fax gateway over the IP network.

STP

Signal Transfer Point; an SS7 router or packet switch whose main function is to relay messages between service switching points and databases in an SS7 network. STPs are frequently deployed as mated pairs, sharing all traffic between their adjacent signaling points during normal operation but each serving as a backup to the other in the case of a failure.

stream

A grouping of timeslots that usually corresponds to a particular bit-stream of time-domain multiplexed (TDM) serial data on an individual track or wire of a bus. See also TDM.

stub

Functions that map simple local procedure calls into a series of RPC function calls.

subscriber loop

A local loop connection to which a standard telephone is connected. It provides power to the telephone and employs ringing, dial tones, and other audible prompts for call signaling.

subsystem

A sub-identifier for a signaling point, supported by the SCCP protocol. An application using the SCCP service can register to receive messages sent only to a particular SCCP subsystem at their point code. Several applications can make simultaneous use of the SCCP data "pipe."

SUCCESS

A return code that for asynchronous functions signifies the function was initiated. For synchronous functions, SUCCESS means that the function was completed. Note that for functions that require board resources, SUCCESS means that the commands necessary to execute the function on the board were delivered to the board. An error can still be returned in an event later.

SUCCESS_RESPONSE

A return code which indicates data is being returned.

supervised transfer

A call transfer method in which the application controls the transfer process. See also blind transfer.

supervision

In telephony, the process whereby a switching system monitors the status of a line from the inception of a call through its termination. See also call progress.

swish utility

CT Access utility which controls MVIP switches. swish is a tool for interactive or text-file-driven control of MVIP switches. It provides a convenient way to manually try out connections during development to verify the commands that will be given to switches from within CT Access applications that use the Switching service.

switch

In telephony, a device that can connect one of several inputs to one of several outputs.

switch block

The switch on a telephony board that connects the telephone network to the telephony bus. The logical switch is normally referred to as the switch block because it may consist of one or more physical switches or chips.

switch fabric

In the CT Access Point-to-Point Switching service, specifies the topology of a system of boards connected by telephony buses.

switch handle

In CT Access, identifies an open MVIP or H.100 switching device and allows access to the corresponding switch block.

switching

In computer telephony, making connections between telephony boards within a PC chassis both during and between phone calls. Enables an application to share resources and data across different telephony boards.

switching card

A circuit card (board) which contains an MVIP switch block. Since MVIP switching is distributed, systems may contain several switching cards. A given connection may involve more than one switch block on different switching cards.

switching compatible

See MVIP Switching Compatible device.

switching driver

Driver providing the interface between the application switching commands to the physical switch on the device.

Switching service

A CT Access service that provides a set of functions for controlling switch connections on MVIP compliant or H.100 compliant switching devices. This service is based on the MVIP-95 switch model. It can be used with either the MVIP-95 switch model or the MVIP-90 switch model. See also H.100 bus, MVIP, Point-to-Point Switching service.

Synchronization Source (SSRC)

The source of a stream of RTP packets, identified by a 32-bit numeric SSRC identifier carried in the RTP header. All packets from a synchronization source form part of the same timing and sequence number space, so a receiver groups packets by synchronization source for playback. A synchronization source may change its data format, e.g., audio encoding, over time. The SSRC identifier is a randomly chosen value meant to be globally unique within a particular RTP session. A participant need not use the same SSRC identifier for all the RTP sessions in a multimedia session; the binding of the SSRC identifiers is provided through RTCP. If a participant generates multiple streams in one RTP session, for example from separate video cameras, each must be identified as a different SSRC.

synchronous function

A function that does not return until the operation it initiated has completed. See also asynchronous function.