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Appendix A

Glossary

A bit See ABCD bits.
A-law A companding algorithm used in E1 transmissions. Another algorithm, mu-law, is used in North America and Japan (primarily for T1 trunks).
ABCD bits The signaling bits used to carry channel associated signaling on digital CAS trunks and on MVIP streams. The value that these bits take determines or indicates the state of the telephone channel. Many protocols do not use all four bits.
AG board See Alliance Generation board.
AG configuration file A text file containing configuration information for the AG boards in a system. When agmon runs, it configures the boards as described in this file. See also agmon.
agmon Utility program which reads a configuration file and uses it to load and monitor the AG hardware.
Alliance Generation (AG) board
A member of Natural MicroSystems' Alliance Generation family of telephony and voice processing hardware products.
ANI See Automatic Number Identification.
API Application Programming Interface; a library of function calls that allow an application developer to access functionality in a uniform and consistent way.
Automatic Number Identification (ANI)
A telephone network service that provides a called party with the phone number of the calling party. this service is not supported by all CAS protocols.
blocking Call control action taken by an application to refuse any further incoming calls. Depending on the protocol, blocking calls will either tell the Central Office or switch not to offer any calls, or tell the TCP to reject every call that is being offered (not answer, or play busy).
call control The act of setting up, monitoring, and terminating a telephone call.
call progress Functions that allow the application to control call placement. Call progress monitors in-band energy to detect telephone network tones, voice, and other tones such as modems.
CAS See Channel Associated Signaling.
CEPT Conference des administrations Europeenes des Postes et Telecommunications, a standards body that sets standards for services and interfaces.
channel An electronic communications path. In digital telephony, a channel usually refers to a separate connection carried on a digital trunk. Channel information is carried in timeslots, time-division multiplexed into a single continuous stream of information.
Channel Associated Signaling (CAS)
A signaling system in which signaling information is sent for all channels at regular intervals, regardless of whether each channel's state changes. The information for each channel consists of a set of bits (called the ABCD bits). Whenever a channel's state changes, the ABCD bit pattern for that channel changes. On T1 trunks, this information is "buried" in the voice information using robbed-bit signaling. On E1 trunks, this signaling is carried in a dedicated channel. See also ABCD bits.
compelled sequence An exchange of in-band signaling during call setup, where each party waits for receipt acknowledgment from the other party before sending the next signal.
CT Access Natural MicroSystems' development environment for telephony applications.
DID number See Direct Inward Dial number.
digital Information in a discrete or quantized form. Opposite of analog.
Digital Signal Processor (DSP)
A microprocessor that is designed to perform the calculations required digital processing of analog signals.
Direct Inward Dial number (DID number)
The called number which is collected by the trunk control program and passed back to the application.
DSP See Digital Signal Processor.
DSP program files Software modules that program an AG board's DSPs to perform certain functions. The DSP program files for an AG board to use are specified in the AG configuration file, and are loaded to on-board memory by agmon.
DTMF Dual-Tone-Multi-Frequency; an in-band signaling system that uses two simultaneous voice-band tones for dialing. Also called Touchtone.
EAM Ear and Mouth protocol. See also Pulsed E and M.
E1 A standard for digital telephone carriers. E1 is similar to T1 but operates at 2.048 Mbps and has 32 channels instead of T1's 24.
EUC protocols EUropean digital Channel-associated-signaling protocols. A protocol family including special channel associated signaling protocols used in certain European countries. The protocols use two-bit line signaling, not as specified by CCITT but by national documents. The register signaling is either carried by in-band DTMF tones (not compelled) or by out-of-band decadic pulses.
events Data structures that contain notification of certain conditions or state changes sent from the hardware or service to the application program. All events are represented as a C data structure. The structure informs the application what event occurred and provides additional information specific to the event. An indication that playing a message is done is a typical event. See also DONE event.
full duplex Simultaneous two-way voice and two-way signal data transmission.
gateway application A switching application in which, when an inbound call arrives, the switch places an outgoing call based on the DID information from the inbound call. When the outbound call is answered, the switch answers the inbound call and connects it to the outbound line.
H.100 bus A PCM digital bus standard for integrating various board vendors. Allows boards to share data, signaling and switching information. It is an interoperable superset of the H-MVIP and MVIP-90 telephony buses.
host The PC CPU where the host application runs.
inbound application An application designed to receive inbound calls. See also outbound application.
inbound call A call received by an inbound application, placed by a remote party.
IVR Interactive Voice Response. An application that receives instructions from users and/or provides information to users by means of recorded or synthesized human speech.
IWK International Wink Start protocol; protocol family that includes country-specific variations of the US Wink Start protocol used in particular countries on T1 trunks. The protocol uses one-bit signaling, and performs register signaling by in-band DTMF or MF tones, or by out-of-band decadic pulses.
line A logical telephone connection on which a call can take place.
loopback Connecting the input and outputs of a device locally. This configuration is typically used for testing purposes (also called "back-back").
MF Multi-Frequency; an in-band interoffice tone-based signaling method using pairs of frequencies from a set of six available frequencies.
MFC-R2 ITU standard line protocol for E1 lines using compelled MF tones and channel-associated signaling. Almost every country has a national variant of this standard.
MFS Multi-Frequency compelled Socotel standard protocol: a protocol that uses a one bit steady state line signaling and performs register signaling using MF tones. It uses a compelled scheme that is different from the CCITT or MFC-R2 schemes. MFS is used in only one country (Spain) and only on E1 lines.
mu-law A companding algorithm used in T1 transmissions, primarily in North America and Japan. Another algorithm, A-law, is used for E1 transmission. See also A-law.
MVIP Multi-Vendor Integration Protocol; a PCM digital bus standard for integrating various board vendors. Facilitates software-controlled digital switching within the PC chassis. MVIP interconnects switching and telephony processing boards on a PC.
MVIP bus A high-speed, multiplexed digital telephony "highway" which allows boards to share data, signaling information, and switching information.
NMS Natural MicroSystems Corporation.
off-hook The active state of a customer telephone circuit. The term is derived from old telephone sets where the receiver, when in use, was lifted from a hook attached to a switch. The opposite condition is on-hook.
outbound application An application designed to place outbound calls. See also inbound application.
outbound call A call placed by an application to a remote party.
out-of-band Information carried outside of the audio or voice channel.
pattern An 8 bit sample that is sent out of an output terminus or into an input terminus of a switch block.
PCI Peripheral Component Interconnect. A 32/64 bit local bus inside a PC.
port The meaning of this term can vary. Usually, it refers to a logical entity on a DSP board which can run telephony protocols, play and record voice files, or execute other DSP functions. It is typical to connect such a DSP port to a line interface or a trunk by using MVIP switching. This type or port generally corresponds to a CTA context in the ADI service.
protocol The signaling scheme used on a trunk. Many different protocol standards, and variations of these standards, are in use around the world.
Pulsed E and M Pulsed Ear and Mouth; a telephone signaling system used between two switches that uses two wires called the E lead and the M lead. In analog E and M, the M lead of one switch is connected to the E lead of the other, and vice versa. In digital E and M signaling, a single bit is used to convey signaling states. A common mnemonic is that E stands for ear-lead and M for mouth-lead.
ring The alerting signal to the subscriber or terminal equipment; also the name for one conductor of a wire pair, designated by R. The other is called tip, or T. See also tip.
R1.5 System R1.5; an international protocol family that includes channel associated signaling protocols used for E1 lines in Russia.
R2 Signaling One of several standards for channel associated signaling.
release guard time An interval in which an inbound protocol remains in blocking state after both parties have hung up.
runfile A module of basic low-level software which an AG board requires to operate. The runfile for a board is specified in the AG configuration file. When agmon runs, it transfers the runfile from the host into on-board memory. See also agmon.
SIT See Special Information Tone.
solicited event An event that occurs as a consequence of some function call.
Special Information Tone (SIT)
A sequence of three tones which indicate to a calling party that a telephone network-provided announcement will follow.
stream A group of timeslots; typically, this term refers to the entire set of timeslots on a trunk, or the mapping of those timeslots onto the MVIP bus.
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.
switch In telephony, a device that can connect one of several inputs to one of several outputs. Switches can range in size from an integrated circuit to an entire building.
synchronous function A function that does not return until its operation is complete.
T1 A standard for telephone transmission that multiplexes 24 channels on a single 1.544 Mbps carrier.
TCP See Trunk Control Program.
timeslot On a digital trunk and on the MVIP bus, information in each channel is time-division multiplexed into a single continuous stream of data. The interval in which each channel broadcasts is called a timeslot.
toll category In MFC-R2 and E and M protocols, the digit received by the inbound application that indicates the Group II category of incoming ANI digits. Usually this is the same as the user category, but in some countries it carries the toll category of the call.
trunk A transmission channel connecting two switching machines.
Trunk Control Program (TCP)
A software module designed to run in an AG board's on-board memory, which interfaces a host application with an analog or digital trunk running a certain protocol. The TCP to use is specified in the AG configuration file, and is transferred to the AG board by agmon.
unsolicited events Events that can occur at any time, regardless of the application's current activities.
user category In MFC-R2 and E and M protocols, the digit received by the inbound application that indicates the Group I category of incoming ANI digits; e.g. normal subscriber, operator, maintenance equipment.

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