|Glossary of Terms and Acronyms
Bit Rate): ABR is an ATM bandwidth-allocation service
that adjusts the amount of bandwidth based on the amount of
traffic in the network. ABR service provides a guaranteed
minimum bandwidth capacity but allows data to be bursted at
higher capacities when the network is free.
AHT (Average Hold Time): The average length
of time between the moment a caller finishes dialling and
the moment the call is answered.
ANI (Automatic Number Identification): A
telephone function that transmits the billing number of the
incoming call (Caller ID, for example).
AS (Autonomous System): A group of networks
under mutual administration that share the same routing methodology.
An AS uses an internal gateway protocol and common metrics
to route Packets within the AS, and uses an external gateway
protocol to route packets to other ASs.
ASP (Application Service Provider): An independent,
third-party provider of software-based services delivered
to customers across a wide area network (WAN).
ASR (Answer-Seizure Ratio): The ratio of
successfully connected calls to attempted calls (also called
'Call Completion Rate'). ASRs vary by routes. A typical ASR
to Pakistan is lower than that of Germany. Reasons for this
include the quality of the network and the fact that it's
less likely that a call to Pakistan will encounter a device
such as an answering machine. Built-in IPCB.net QoS Management
Tools track the ASRs for all termination facilities that receive
calls routed through the IPCB.net.
ATA(Analog Telephone Adapter): In our world
ATA refers to am adapter positioned between your POT (Plain
Old Telephone). This device is a small box that enables a
POT to become a VoIP endpoint.
ATM (Asynchronous Transfer Mode): ATM is network
technology based on transferring data in cells or packets
of fixed size. The cell used with ATM is relatively small
(53 bytes) compared to the units used with older technologies.
The small, constant cell size allows ATM equipment to multiplex
efficiently video, audio, and computer data over the same
Backbone: A very-high-speed
network spanning the world from one major metropolitan area
to another. Such networks are typically provided by national
Internet Service Providers (ISPs). Local ISPs connect to the
backbone in order to transport data.
Bad Frame Interpolation: Bad Frame Interpolation interpolates
lost/corrupted packets by using the previously received voice
frames. It increases voice quality by making the voice transmission
more robust in bursty error environments.
Bandwidth: The maximum data carrying capacity of a transmission
link. For data networks, bandwidth is usually expressed in
bits per second (bps).
BRI (Basic-Rate Interface): the basic ISDN configuration,
which consists of two B-channels that can carry voice or data
at rate of 64Kbps, and one D-channel, which carries call-control
information. Another type of ISDN configuration is called
Primary-Rate Interface (PRI), which consists of 23 B-channels
(30 in Europe) and one D-channel.
Buffer: A temporary data storage area, usually in RAM. The
purpose of most buffers is to act as a holding area, enabling
the CPU to manipulate data before transferring it to a device.
Because the processes of reading and writing data to a disk
are relatively slow, many programs keep track of data changes
in a buffer and then copy the buffer to a disk. For example,
word processors employ a buffer to keep track of changes to
files. Then when you save the file, the word processor updates
the disk file with the contents of the buffer. This is much
more efficient than accessing the file on the disk each time
you make a change to the file.
Call: Establishment of (or
an attempt to establish) voice connection between two endpoints,
or between two points which provide a partial link (e.g. a
trunk) between two endpoints.
Call Deflection: Call Diversion or Call Forwarding
allows a called endpoint to redirect the unanswered call to
CBR (Constant Bit Rate): often referred to as Class A quality
of service. CBR is an ATM bandwidth-allocation service that
requires the user to determine a fixed bandwidth requirement
at the time the connection is set up so that the data can
be sent in a steady stream. CBR service is often used when
transmitting fixed-rate uncompressed video.
CDR (Call Detail Record): Information regarding a single
call collected from the switch and available as an automatically
generated downloadable report for a requested time period.
The report contains information on the number of calls, call
duration, call origination and destination, and billed amount.
IPCB.net Members use CDR reports to bill retail customers
and settle with their partners on a wholesale level.
CENTREX (Central office EXchange service): a type of PBX
service in which switching occurs at a local telephone station
instead of at the company premises. Typically, the telephone
company owns and manages all the communications equipment
necessary to implement the PBX and then sells various services
to the company.
CLEC (Competitive Local Exchange Carrier): A telephone company
that competes with an incumbent local exchange carrier (ILEC),
such as a Regional Bell Operating Company (RBOC), GTE, ALLNET,
Telus, Allstream etc. With the passage of the Telecommunications
Act of 1996, there has been an explosion in the number of
CLECs. The Act allows companies with CLEC status to use ILEC
infrastructure in two ways: 1) Access to UNEs - Important
to CLEC telecommunications networking is the availability
of unbundled network elements or UNEs (through a collocation
arrangement). UNEs are defined by the Act as any "facility
or equipment used in the provision of a telecommunications
service," as well as "features, functions, and capabilities
that are provided by means of such facility or equipment."
For CLECs the most important UNE available to them is the
local loop, which connects the ILEC switches to the ILEC's
present customers. With the local loop, CLECs will be able
to connect their switches with the ILEC's switches, thus giving
them access to ILEC customers.2) Resale - Another option open
to CLECs is the resale strategy. The Act states that any telecommunications
services ILECs offer at retail, must be offered to CLECs at
a wholesale discount. This saves the CLEC from having to invest
in switches, fiber optic transmission facilities, or collocation
arrangements. In any case, a CLEC may decide on one or the
other or even both. CLEC status is very beneficial, especially
for ISPs, who may easily get access to the copper loops and
other switching elements necessary to provide xDSL services.
Codec: The term codec is a contraption of COder and DECoder.
The codec is where the analog to digital transformation is
performed. In the PSTN, the Pulse Code Modulation (PCM) scheme
is used to generate a 64kbps stream. More “economical”
coding schemes have been designed to reduce this stream to
32, 16, and even 8 kbps. The main ITU codec standards are
G.711, G.722, G.726, G.728, G.729, G.723. This reduction in
the number of kbps required comes at the price of reduced
quality of the voice signal, thus a required trade-off between
bandwidth and quality of service.
Connection-Oriented: Mode of communication in which a connection
must be established between the transmitter and receiver before
transmission of user data. This can be done by switching a
circuit or by setting up a logical channel. A well-known connection-oriented
protocol is TCP. Connection-oriented is the opposite of connectionless.
Connectionless: Mode of communication in which a connection
(circuit or logical channel) does not need to be set up for
data transmission between the transmitter and receiver. It
is the underlying protocol for packet-switched transmission.
The individual data packets can go from the transmitter to
the receiver via different paths. A well-known connectionless
protocol is UDP.
DHCP (Dynamic Host Configuration
Protocol): A protocol for assigning dynamic IP addresses to
devices on a network. With dynamic addressing, a device can
have a different IP address every time it connects to the
network. In some systems, the device's IP address can even
change while it is connected. DHCP also supports a mix of
static and dynamic IP addresses.
Dynamic addressing simplifies network administration because
the software keeps track of IP addresses rather than requiring
an administrator to manage the task. This means that a new
computer can be added to a network without the hassle of manually
assigning it a unique IP address. Many ISPs use dynamic IP
addressing for dial-up users.
Dial-peer: Addressable call endpoint -- a software structure
that binds a dialed digit string to a voice port or IP address
of the destination gateway. Several dial peers always exist
on each router in the network, and at least two will be involved
in making a call across the network, one on the originating
end and one on the terminating end. In Voice over IP, there
are two kinds of dial peers: POTS and VoIP. VoIP peers point
to specific VoIP devices.
Dial-peer hunting: Process when the originating router tries
to establish call on different dial peers if the originating
router receives a user-busy invalid number or an unassigned-number
disconnect cause code from a destination router.
DID (Direct Inward Dialling): Traditionally a DID is a PBX
that has been given individual phone numbers which is different
than extensions from one central phone number. The same is
possible with VoIP.
DiffServ (Differentiated Services): is a QoS (quality of
service) protocol for routers that prioritizes IP voice over
other data traffic to help preserve voice quality even when
network traffic is heavy.
DLC (Digital Loop Carrier): A system for transmitting digital
multiplexed data signals using existing cabling for distribution.
The digital loop carrier begins the transmission at the central
office on a high-speed digital line, such as T1, and routes
the transmission to a remote digital terminal, which then
converts the signal into a form that can be passed on to low-speed
lines for routing to the end users telephone or computer.
The process is reversed when transmissions are sent from the
end user, where the system collects transmissions and multiplexes
them so they can be sent in the aggregate to the central office
of the local loop.
DNIS (Dialed Number Identification Service): A telephone
function that sends the dialled telephone number to the answering
DSLAM (Digital Subscriber Line Access Multiplexer): A mechanism
at a phone company's central location that links many customer
DSL connections to a single high-speed ATM line. When the
phone company receives a DSL signal, an ADSL modem with a
POTS splitter detects voice calls and data. Voice calls are
sent to the PSTN, and data are sent to the DSLAM, where it
passes through the ATM to the Internet, then back through
the DSLAM and ADSL modem before returning to the customer's
PC. More DSLAMs a phone company has, the more customers it
DTMF (Dual-Tone Multifrequency): The audio signals made from
pressing the buttons on a touch-tone telephone.
Dynamic Jitter Buffer: Collects voice packets, stores them,
and shifts them to the voice processor in evenly spaced intervals
to reduce any distortion in the sound.
Dynamic NAT (Dynamic Network Address Translator): A type
of NAT in which a private IP address is mapped to a public
IP address drawing from a pool of registered (public) IP addresses.
Typically, the NAT router in a network will keep a table of
registered IP addresses, and when a private IP address requests
access to the Internet, the router chooses an IP address from
the table that is not at the time being used by another private
IP address. Dynamic NAT helps to secure a network as it masks
the internal configuration of a private network and makes
it difficult for someone outside the network to monitor individual
usage patterns. Another advantage of dynamic NAT is that it
allows a private network to use private IP addresses that
are invalid on the Internet but useful as internal addresses.
E&M (Ear and Mouth):
is the interface on a VOIP device that allows it to be connected
to analog PBX trunk ports (tie lines).
E.164: The international public telecommunication numbering
plan. An E.164 number uniquely identifies a public network
termination point and typically consists of three fields,
CC (country code), NDC (national destination code), and SN
(subscriber number), up to 15 digits in total.
Endpoint: SIP or H.323 terminal or Gateway. An endpoint can
Call and be Called. It generates and terminates the information
Failed Call: An attempted
Call that does not receive the connect message. Such calls
are not billed.
Fiber Optics: Is a cable and technology that uses glass or
plastic threads (fiber) to transmit data, each fiber is capable
of transmitting messages modulated onto light waves. Fiber
optics has several advantages over traditional metal communications
lines: 1) Fiber optic cables have a much greater bandwidth
than metal cables. This means that they can carry more data.
2) Fiber optic cables are less susceptible than metal cables
to interference. 3) Fiber optic cables are much thinner and
lighter than metal wires. 4) Data can be transmitted digitally
(the natural form for computer data) rather than analogically.
The main disadvantage of fiber optics is that the cables are
expensive to install. In addition, they are more fragile than
wire and are difficult to split .Fiber optics is a particularly
popular technology for local-area networks. In addition, telephone
companies are steadily replacing traditional telephone lines
with fiber optic cables. In the future, almost all communications
will employ fiber optics.
Firewall: A system designed to prevent unauthorized access
to or from a private network. Firewalls can be implemented
as hardware, software, or a combination of both. All messages
entering or leaving the intranet pass through the firewall,
which examines each message and blocks those that do not meet
the security criteria specified on the firewall.
Forward Error Correction: Increases voice quality by recovering
lost or corrupted packets.
FXO (Foreign Exchange Office): And FXS (Foreign Exchange Station):
FXS and FXS stand for Foreign Exchange Subscriber and Foreign
Exchange Office respectively. The FXS interface delivers POTS
service from the local phone company (from the Central Office).
The FXS interface provides dial tone, battery current, and
ring voltage to the subscriber device. The FXO interface receives
POTS service from the local phone company (from the switch
at the CO). The FXO interface provides on-hook and off-hook
Gatekeeper: The central control entity that performs management
functions in a Voice and Fax over IP network and for multimedia
applications such as video conferencing. Gatekeepers provide
intelligence for the network, including address resolution,
authorization, and authentication services, the logging of
Call Detail Records, and communications with network management
systems. Gatekeepers control bandwidth, provide interfaces
to existing legacy systems, and monitor the network for engineering
purposes as well as for real-time network management and load
balancing. This function is variously referred to as Call
Gateway: In IP telephony, a network device that converts
voice and fax calls, in real time, between the public switched
telephone network (PSTN) and an IP network. The primary functions
of an IP gateway include voice and fax compression/ decompression,
packetization, call routing, and control signaling. Additional
features may include interfaces to external controllers, such
as Gatekeepers or Softswitches, billing systems, and network
Grace Period: The time interval at the beginning of a call,
measured in seconds, that is not billed. IPCB.net fee and
the Routing fee do not apply.
Hairpin: Telephony term
that means to send a call back in the direction that it came
from. For example, if a call cannot be routed over IP to a
gateway that is closer to the target telephone, the call typically
is sent back out the local zone, back the way from which it
Hop off: Point at which
a call transitions from H.323 to non-H.323, typically at a
gateway. "be hopped-off locally" means "be
hairpinned" Example from documentation: "If the
called address does not match any known zone prefixes, the
gatekeeper will attempt to hairpin the call out through a
IDS (Intrusion Detection
System): Inspects all inbound and outbound network activity
and identifies suspicious patterns that may indicate a network
or system attack from someone attempting to break into or
compromise a system. IDS differs from a firewall in that a
firewall looks out for intrusions in order to stop them from
happening. The firewall limits the access between networks
in order to prevent intrusion and does not signal an attack
from inside the network. An IDS evaluates a suspected intrusion
once it has taken place and signals an alarm. An IDS also
watches for attacks that originate from within a system.
IETF (Internet Engineering Task Force): One of two technical
working bodies in the Internet Activities Board. The IETF
meets three times a year to set technical standards for the
IHV (Independent Hardware Vendor): Hardware-manufacturing
company specializing in specific types of hardware device
and not a complete computer system. The IHV typically also
provides the software drivers for its hardware devices.
ILEC (Incumbent Local Exchange Carrier): An ILEC is a telephone
company that was providing local service when the Telecommunications
Act of 1996 was enacted. Compare with CLEC, a company that
competes with the already established local telephone business.
Integrated T1: Comprised of 24 64Kbps channels, T1 lines
can be used for a diverse number of applications. Commonly
referred to as an integrated T1 or channelized T1, this highly
flexible circuit is designed for businesses that need to run
multiple services over the same line. Common applications
for integrated T1 service include, Frame Relay/dedicated long
distance and Internet/point-to-point. Often confused with
a fractional T1, integrated service is made up of multiple
fractional T1 services.
IP Centrex: IP Centrex delivers such services as call hold,
call transfer, last number look-up and redial, call forward,
three-way calling, but does it on a packet-based network.
IP Telephony: The transmission of voice and fax phone calls
over data networks that uses the Internet Protocol (IP). IP
telephony is the result of the transformation of the circuit-switched
telephone network to a packet-based network that deploys voice-compression
algorithms and flexible and sophisticated transmission techniques,
and delivers richer services using only a fraction of traditional
digital telephony’s usual bandwidth. Compare with VoIP.
ISDN (Integrated Services Digital Network): International
communications standard for sending voice, video, and data
over digital telephone lines or normal telephone wires. ISDN
supports data transfer rates of 64 Kbps (64,000 bits per second).
There are two types of ISDN: 1) Basic Rate Interface (BRI)
-- consists of two 64-Kbps B-channels and one D-channel for
transmitting control information. 2) Primary Rate Interface
(PRI) -- consists of 23 B-channels and one D-channel (U.S.)
or 30 B-channels and one D-channel (Europe). The original
version of ISDN employs baseband transmission. Another version,
called B-ISDN, uses broadband transmission and is able to
support transmission rates of 1.5 Mbps. B-ISDN requires fiber
optic cables and is not widely available.
ITSP (Internet Telephony Service Provider): Same as VoIP
Jitter: The variation in
the amount of Latency among Packets being received.
LAN (A local area network):
began as a group of computers and associated devices that
shared a common communications line or wireless link and typically
shared the resources of a server within a small geographic
area (for example, within an office building). This architecture
is seldom used today. Indeed, computers are connected to a
hub where LAN switching occurs. Rather than the wire, it is
now the hub backplane that is shared.
Latency: (Also called delay) is the amount of time it takes
a Packet to travel from source to destination. Together, Latency
and Bandwidth define the speed and capacity of a network.
Licensed Software: The "harvester software" and
any other software provided by IPCB.net to a Member for the
purpose of record keeping, accounting, and/or access to IPCB.net
services, and including IPCB-provided documentation.
Load Balancing: Distribution of calls among terminating Gateways
based on the Priorities and Weights assigned by the Buyer.
Login ID: A string of digits identifying an IPCB.net Registered
User. Together with the Password, the Login ID is used to
authorize a user's access to the IPCB.net trading floor. The
Login ID and Password are automatically e-mailed to a potential
IPCB.net Member after filling out a Registration.
MAC Address (Media Access
Control): Hardware address that uniquely identifies each node
of a network. In IEEE 802 networks, the Data Link Control
(DLC) layer of the OSI Reference Model is divided into two
sub layers: the Logical Link Control (LLC) layer and the Media
Access Control (MAC) layer. The MAC layer interfaces directly
with the network medium. Consequently, each different type
of network medium requires a different MAC layer.
On networks that do not conform to the IEEE 802 standards
but do conform to the OSI Reference Model, the node address
is called the Data Link Control (DLC) address.
MGCP (Media Gateway Control Protocol): A protocol complementary
to H.323 and SIP, designed to control media gateways from
external call control elements in decomposed gateway architectures.
Working in conjunction with the Gateway Location Protocol
(GLP), MGCP enables a caller with a PSTN phone number to locate
the destination device and establish a session. It provides
the gateway-to-gateway interface for the Session Initialization
Protocol (SIP). MGCP is meant to simplify standards for the
new Voice over Packet technology by eliminating the need for
complex, processor-intense IP telephony devices, thus simplifying
and lowering the cost of these terminals.
Minimum Duration: The minimum billed call duration up to
which all shorter calls are rounded in seconds.
MPLS (Multi Protocol Label Switching): As the Internet keeps
growing, the fundamental packet forwarding function performed
by routers becomes ever more complex. Such complexity obviously
increases processing delays and reduces traffic throughput.
Label switching has proved an efficient mechanism to reduce
that complexity. As indicated by its name, label switching
is a technique that forwards packets on the basis of an appended
label as opposed to the packet destination address in the
traditional Internet. A few proprietary schemes were developed
before the IETF standardized the concept under the Multi Protocol
Label Switching (MPLS) name.
MPLS is referred to as a layer 2.5 protocol as it stands between
the Network layer (IP, layer 3) and the Link layer (layer
2) of the OSI stack.
Among the many attributes of MPLS, we may list its role in
the support of: traffic engineering, QoS mechanisms, IP-based
NAT (Network Address Translation):
an Internet standard that enables a local-area network (LAN)
to use one set of IP addresses for internal traffic and a
second set of addresses for external traffic. A NAT box located
where the LAN meets the Internet makes all necessary IP address
translations. NAT serves three main purposes: 1) Provides
a type of firewall by hiding internal IP addresses. 2) Enables
a company to use more internal IP addresses. Since they're
used internally only, there's no possibility of conflict with
IP addresses used by other companies and organizations. 3)
Allows a company to combine multiple ISDN connections into
a single Internet connection.
NIDS (Network Intrusion Detection system): Is similar to
IDS but individual packets flowing through a network are analyzed.
The NIDS can detect malicious packets that are designed to
be overlooked by a firewall’s simplistic filtering rules.
In a host-based system, the IDS examines at the activity on
each individual computer or host.
OC (Optical Carrier): A method to specify
the speed of fiber optic networks conforming to the SONET
standard. The following illustrates the speeds for common
- OC-1 = 51.85Mbps - OC-3 = 155.52Mbps - OC-12 = 622.08Mbps
- OC-24 = 1.244Gbps - OC-48 = 2.488Gbps - OC-192 = 9.952Gbps
- OC-255 = 13.21Gbps
OEM (Original Equipment Manufacturer): a misleading term
for a company that has a special relationship with computer
producers. OEMs buy computers in bulk and customize them for
a particular application. They then sell the customized computer
under their own name. The term is really a misnomer because
OEMs are not the original manufacturers -- they are the customizers
OSI (Open System Interconnection): An ISO standard for worldwide
communications that defines a networking framework for implementing
protocols in seven layers.
OSI (Open Source Initiative): a non-profit organization that
promotes the integrity of the open source definition by certifying
products with the OSI Certified Open Source Software mark.
OSI is comprised of board members who make up its directorship
and is not a membership organization.
OSS (Operations Support System): The generic term for a suite
of programs that enable an enterprise to monitor, analyze
and manage a network system. The term originally was applied
to communications service providers, referring to a management
system that controlled telephone and computer networks. The
term has since been applied to the business world in general
to mean a system that supports an organization’s network
OSS (Open Source Software):
Packet: In data communication,
the basic logical unit of information transferred.
PBX (Private Branch eXchange): An in-house telephone usually
within an enterprise switching system that interconnects telephone
extensions to each other as well as to the outside telephone
network. Users of the PBX share a certain number of outside
lines for making telephone calls external to the PBX.
Most medium-sized and larger companies use a PBX because it's
much less expensive than connecting an external telephone
line to every telephone in the organization. In addition,
it's easier to call someone within a PBX because the number
you need to dial is typically just 3 or 4 digits. A new variation
on the PBX theme is the centrex, which is a PBX with all switching
occurring at a local telephone office instead of at the company's
PPP (Point-to-Point Protocol): One method of connecting a
computer to the Internet. PPP is more stable than the older
SLIP protocol and provides error checking features. Working
in the data link layer of the OSI model, PPP sends the computer's
TCP/IP packets to a server that puts them onto the Internet.
PPPOE (Point to Point Protocol of Ethernet): PPPoE relies
on two widely accepted standards: PPP and Ethernet. PPPoE
is a specification for connecting the users on an Ethernet
to the Internet through a common broadband medium, such as
a single DSL line, wireless device or cable modem. All the
users over the Ethernet share a common connection, so the
Ethernet principles supporting multiple users in a LAN combine
with the principles of PPP, which apply to serial connections.
POTS (Plain Old Telephone Service): The standard telephone
service that most homes use. In contrast, telephone services
based on high-speed, digital communications lines, such as
ISDN, are not POTS. The main distinctions between POTS and
non-POTS services are speed and bandwidth. POTS is generally
restricted to about 52 Kbps (52,000 bits per second). The
PSTN (Public Switch Telephone Network) is the network supporting
the POTS service. While they form a tight pair, they are not
the same. POTS should not be confused with pot, an abbreviation
of potentiometer. All references to POTS in the RARIS web
site refer to the Plain Old Telephone Service.
PRI (Primary Rate Interface): Short for Primary-Rate Interface,
a type of ISDN service designed for larger organizations.
PRI includes 23 B-channels (30 in Europe) and one D-Channel.
In contrast, BRI (Basic-Rate Interface), which is designed
for individuals and small businesses, contains just two B-channels
and one D-channel. PRI service is generally transmitted through
a T-1 line (or an E1 line in Europe).
PSTN (Public Switched Telephone Network): This term refers
to the international telephone system based on copper wires
carrying analog voice data. This is in contrast to newer telephone
networks base on digital technologies, such as ISDN.
QoS (Quality of Service): Traditionally,
in the PSTN, QoS referred to the “quality of the line”.
This quality was measured on a scale from 1 (very poor quality)
to 5 (very good quality). The impact of the introduction of
a new technology was measured by having groups of individuals
listen to “transmission samples” and rate (from
1 to 5) the perceived quality of communication. The overall
rating is thus appropriately named the Mean Opinion Score
In the early days of the Internet, only computer-to-computer
traffic was flowing on the Internet and the “best-effort”
service provided was adequate for this single type of traffic.
With the arrival of the web and the multiplication of Internet-based
applications, the need for classes of service appeared. Each
class of service is characterized by a set of performance
attributes that it offers (ex. low packet delay, low packet
loss, etc). QoS mechanisms have been designed in order to
maintain efficient coexistence of these Classes of Service.
QoS mechanisms control flowing traffic in order to ensure
that each Class of Service is provided, by the network, adequate
processing and transmission resources to maintain specific
levels of service per class.
RAS (Registration, Admission,
Status): A management protocol between terminals and Gatekeepers.
Route: A set of parameters predefined by IPCB.net to facilitate
routing of traffic between the Gateways/Gatekeepers controlled
by an IPCB.net Member either via ownership or via a partnership
with the owner. Along with specifying other parameters, an
IPCB.net Member using the Gatekeeping Service assigns to a
Route values specifying the details of both originating and
RSVP (Resource Reservation Protocol): Protocol that supports
the reservation of resources across an IP network. Applications
running on IP end systems can use RSVP to indicate to other
nodes the nature (bandwidth, jitter, maximum burst, and so
on) of the packet streams they want to receive. RSVP depends
on IPv6. Also known as Resource Reservation Setup Protocol.
RTP (Real-Time Transport Protocol): Commonly used with IP
networks. RTP is designed to provide end-to-end network transport
functions for applications transmitting real-time data, such
as audio, video, or simulation data, over multicast or unicast
network services. RTP provides such services as payload type
identification, sequence numbering, time stamping, and delivery
monitoring to real-time applications.
SIP (Session Initiation Protocol): An
application-layer control protocol, a Signaling protocol for
Internet Telephony. SIP can establish sessions for features
such as audio/videoconferencing, interactive gaming, and call
forwarding to be deployed over IP networks thus enabling service
providers to integrate basic IP telephony services with Web,
e-mail, and chat services. In addition to user authentication,
redirect and registration services, SIP Server supports traditional
telephony features such as personal mobility, time-of-day
routing and call forwarding based on the geographical location
of the person being called.
SLA (Service Level Agreement): a contract between an ASP
or SP and the end user which stipulates and commits a required
level of service. An SLA should contain a specified level
of service, support options, enforcement or penalty provisions
for services not provided, a guaranteed level of system performance
as relates to downtime or uptime, a specified level of customer
support and what software or hardware will be provided and
for what fee.
Softswitch: (Also called a Proxy Gatekeeper, Call Server,
Call Agent, Media Gateway Controller, or Switch Controller)
Software used to bridge a public switched telephone network
and voice over Internet by separating the call control functions
of a phone call from the media gateway (transport layer).
Softswitch performs call control functions such as protocol
conversion, authorization, accounting and administration operations.
SoftSwitching Service: IPCB.net Softswitch service allows
IPCB.net Members to bill, route and monitor IP telephony traffic
between their gateways and the gateways of their partners.
For more information on this please refer to the corresponding
section of this site.
T1: 1.544-Mbps point-to-point
dedicated digital circuit provided by the telephone companies
consisting of 24 channels.
TCP (Transmission Control Protocol): TCP is one of the main
protocols in TCP/IP networks. Whereas the IP protocol deals
only with packets, TCP enables two hosts to establish a connection
and exchange streams of data. TCP guarantees delivery of data
and also guarantees that packets will be delivered in the
same order in which they were sent.
TCP/IP (Transmission Control Protocol/Internet Protocol):
The suite of communications protocols used to connect hosts
on the Internet. TCP/IP uses several protocols, the two main
ones being TCP and IP. TCP/IP is built into the UNIX operating
system and is used by the Internet, making it the de facto
standard for transmitting data over networks. Even network
operating systems that have their own protocols, such as Netware,
also support TCP/IP.
ToS (Type of Service): A method of setting precedence for
a particular type of traffic for QoS. ToS is an 8-bit field
in the IP datagram header that identifies the relative priority
of one packet over another. Networking devices use this field
to prioritize packets appropriately and place them in different
queues if necessary.
Trunk: A communications channel between two points, typically
referring to large-bandwidth telephone channels between switching
centers that handle many simultaneous voice and data signals.
Trunking: Trunking means that several connections in a network
may be established simultaneously, and that setup of connections
proceeds automatically using the channels available at the
time in question. In this way many users may share a few connections,
and if the number of connections is increased, the capacity
of the network is increased more than proportionally. This
means that an optimal trunking effect is obtained in very
UBR (Unspecified Bit Rate): or Class
D quality of service. UBR is the ATM bandwidth-allocation
service that does not guarantee any throughput levels and
uses only available bandwidth. UBR is often used when transmitting
data that can tolerate delays.
UDP (User Datagram Protocol): A connectionless protocol that,
like TCP, runs on top of IP networks. Unlike TCP/IP, UDP/IP
provides very few error recovery services, offering instead
a direct way to send and receive datagrams over an IP network.
It's used primarily for broadcasting messages over a network.
UPS (Uninterruptible Power Supply): A power supply that has
a built-in battery to maintain power in the event of a power
outage. Typically, a UPS keeps a computer or servers running
for several minutes/hours after a power outage, enabling you
to save data that is in RAM and shut down the computer gracefully.
Many UPSs now offer a software component that enables you
to automate backup and shut down procedures in case there's
a power failure while you're away from the computer.
There are two basic types of UPS systems: An SPS monitors
the power line and switches to battery power as soon as it
detects a problem. The switch to battery, however, can require
several milliseconds, during which time the computer is not
receiving any power. An on-line UPS avoids these momentary
power lapses by constantly providing power from its own inverter,
even when the power line is functioning properly. In general,
on-line UPSs are much more expensive than SPSs.
VBR (Variable Bit Rate):
or Class B quality of service VBR is the ATM bandwidth-allocation
service that allows users to specify a throughput capacity
(i.e., a peak rate) and a sustained rate but data is not sent
evenly. VBR is often used when transmitting compressed packetized
voice and video data, such as videoconferencing.
VLAN (Virtual Local Area Network): A network of computers
that behave as if they are connected to the same wire even
though they may actually be physically located on different
segments of a LAN. VLANs are configured through software rather
than hardware, which makes them extremely flexible. One of
the biggest advantages of VLANs is that when a computer is
physically moved to another location, it can stay on the same
VLAN without any hardware reconfiguration.
VoIP (Voice over IP): The capability to carry normal telephony-style
voice over an IP-based Internet with POTS-like functionality,
reliability, and voice quality. VoIP enables a router to carry
voice traffic (for example, telephone calls and faxes) over
an IP network. In VoIP, the DSP segments the voice signal
into frames, which then are coupled in groups of two and stored
in voice packets. These voice packets are transported using
IP in compliance with ITU-T specification H.323.
VoIP Trunking: Service providers can use this application
to connect enterprise and call center customers directly to
their VoIP network. By bypassing local operators and toll
charges, the VoIP trunking application enables service providers
to offer attractive termination rates for both domestic and
international long distance calling. This application connects
seamlessly to the enterprise/call center's PBX, allowing employees
to make off-net calls at reduced rates.
VPDN (Virtual Private Dial-up Network): Also known as virtual
private dial network. A VPDN is a network that extends remote
access to a private network using a shared infrastructure.
VPDNs use Layer 2 tunnel technologies (L2F, L2TP, and PPTP)
to extend the Layer 2 and higher parts of the network connection
from a remote user across an ISP network to a private network.
VPDNs are a cost effective method of establishing a long distance,
point-to-point connection between remote dial users and a
VPN (Virtual Private Network): Enables IP traffic to travel
securely over a public TCP/IP network by encrypting all traffic
from one network to another. A VPN uses “tunneling”
to encrypt all information at the IP level.
WEP (Wired Equivalent Privacy): A security
protocol for wireless local area networks (WLANs) defined
in the 802.11 standard. WEP is designed to provide the same
level of security as that of a wired LAN. LANs are inherently
more secure than WLANs because LANs are somewhat protected
by the physicalities of their structure, having some or all
part of the network inside a building that can be protected
from unauthorized access. WLANs, which are over radio waves,
do not have the same physical structure and therefore are
more vulnerable to tampering. WEP aims to provide security
by encrypting data over radio waves so that it is protected
as it is transmitted from one end point to another. However,
it has been found that WEP is not as secure as once believed.
WEP is used at the two lowest layers of the OSI model - the
data link and physical layers; it therefore does not offer
WPA (Wi-Fi Protected Access): A Wi-Fi standard that was designed
to improve upon the security features of WEP. The technology
is designed to work with existing Wi-Fi products that have
been enabled with WEP (i.e., as a software upgrade to existing
hardware), but the technology includes two improvements over
Improved data encryption through the temporal key integrity
protocol (TKIP). TKIP scrambles the keys using a hashing algorithm
and, by adding an integrity-checking feature, ensures that
the keys haven’t been tampered with.
User authentication, is generally missing in WEP even through
the Extensible Authentication Protocol (EAP). WEP regulates
access to a wireless network based on a computer’s hardware-specific
MAC address, which is relatively simple to be sniffed out
and stolen. EAP is built on a more secure public-key encryption
system to ensure that only authorized network users can access
the network. It should be noted that WPA is an interim standard
that will be replaced with the IEEE’s 802.11i standard
upon its completion.