User guide

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Glossary
Multi-Tech Systems, Inc. MultiVOIP User Guide
Foreign Exchange (FX): A CO trunk with access to a distant CO, allowing ease of access and flat-rate calls anywhere in the
foreign exchange area.
Foreign Exchange Office (FXO): provides local phone service from a CO outside of ("foreign" to) the subscriber's exchange area.
In simple form, a user can pick up the phone in one city and receive a tone in the foreign city.
Connecting a POTS phone to a computer telephony system via a T1 link requires a channel bank configured for the FX connection.
To generate a call from the POTS set to the computer telephony system, a FXO connection must be configured.
Foreign Exchange Station (FXS): See FX, FXO. To generate a call from the computer telephony system to the POTS set, a FXS
connection must be configured.
Forward Explicit Congestion Notification (FECN): A bit that tells you that a certain frame on a particular logical connection has
encountered heavy traffic. The bit provides notification that congestion-avoidance procedures should be initiated in the same
direction of the received frame. See also BECN (Backward Explicit Congestion Notification).
G
Gatekeeper: An H.323 entity that provides address translation, control access, and sometimes bandwidth management to the LAN
for H.323 terminals, Gateways, and MCUs.
Gateway: 1. A functional unit that interconnects two computer networks with different network architectures. A gateway connects
networks or systems of different architectures. A bridge interconnects networks or systems with the same or similar architectures. 2.
A network that connects hosts. 3. An H.323 entity that provides real-time, two-way communications between H.323 terminals on the
LAN and other ITU terminals on a WAN, or to another H.323 Gateway.
Graphical User Interface (GUI): A type of computer interface consisting of a visual metaphor of a real-world scene, often of a
desktop. Within that scene are icons, representing actual objects, that the user can access and manipulate with a pointing device.
H
H.323: An umbrella recommendation from the International Telecommunications Union (ITU) that sets standards for multimedia
communications over Local Area Networks (LANs) that do not provide a guaranteed Quality of Service (QoS).
H.323 Entity: Any H.323 component, including terminals, Gateways, Gatekeepers, Multipoint Controllers (MCs), Multipoint
Processors (MPs), and Multipoint Control Units (MCUs).
Handshaking: A process that two modems go through at the time of call setup to establish synchronization over the data commu-
nications link. It is a synchronization and negotiation process accomplished by the exchange of predefined, mutually recognized
control codes.
High-level Data Link Control (HDLC): An ISO standard, bit-oriented data communications protocol that provides nearly error-free
data transfers.
I
Hexadecimal: A base 16 numbering system used to represent binary values. Hex uses the numbers 0-9 and the letters A-F:
usually notated by an "h" (e.g., "4CF h", read "four charley fox, hex"). The result is that one hex digit represents a 4-bit value.
Implicit congestion management: A method of informing the terminal that the network is busy. This method relies on the end-
system protocol to detect and fix the congestion problem. (TCP/IP is an example of a protocol using only implicit congestion
management.) See also "explicit congestion management".
In-band: Refers to the type of signalling over the conversion path on an ISDN call. Contrast "out-of-band".
Internet: Refers to the computer network of many millions of university, government and private users around the world. Each user
has a unique Internet Address.
Internet Address (IP Address): A unique 32-bit address for a specific TCP/IP host on a network. Normally printed in dotted
decimal format (e.g., 129.128.44.227).
Internet Protocol (IP): A protocol used to route data from its source to its destination in an Internet environment. The Internet
Protocol was designed to connect to local area networks. Although there are many protocols that do this, IP refers to the global
system of interconnecting computers. It is a highly distributed protocol (each machine only worries about sending data to the next
step in the route).
Internetwork Packet Exchange (IPX): A NetWare communications protocol used to route messages from one node to another.
IPX packets include network addresses and can be routed from one network to another. An IPX packet can occasionally get lost
when crossing networks, thus IPX does not guarantee delivery of a complete message. Either the application has to provide that
control, or NetWare's SPX protocol must be used.
Interoperable: Devices from different vendors that can exchange information using a standard's base protocol.