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How does a telephone number work?
Telephone numbers come in three parts:
| 508 |
883 |
1000 |
| NPA |
NXX |
Subscriber Code |
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When you think about how telephone numbers work, this
about your mailing address. If you want to send a letter
to someone you put their address on it and include your
address in the return corner of the envelope. The postal
service will then route the letter by the address on
the envelope. Your address is structured just like a
telephone number: the zip code indicates a larger area,
your street name narrows down the region and then finally
your house number indicates your exact location.
Your phone number is similar in nature and function.
It helps narrow down your location so callers can reach
you easily and directly, without any outside assistance:
- NPA (area code) indicates a general, larger area
- NXX (three-digit exchange) narrows that area down
- Subscriber code is specific to your phone/location
- What is ISDN?
- What is a PRI ISDN?
- What is a BRI ISDN?
- What is VoIP?
- What is an IP address?
- What is a Router?
- What is a LAN?
- What is a MAN?
- What is a WAN?
- What is WiMax?
- What is a Data Network?
- What is ADSL?
- What is SDSL?
- What is a Firewall?
- What is a DMZ?
- What is SIP?
- What is MPLS?
- What is Network Latency?
- What is Ping?
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- What is ISDN?
Integrated Services Digital Network (ISDN) is fully
digital telephone service, providing data, voice,
and video channels over the existing phone network.
While most of the current phone network is already
digital, ISDN replaces the final analog section connecting
the local exchange with individual houses or offices
to create a fully digital connection.
Not only is ISDN much faster than a standard analog
telephone connection, but also its multiple channels
allow you to use several devices (such as a telephone,
computer, and fax) simultaneously on the same line.
You usually obtain ISDN service from a telephone company
and Internet service provider. There are two different
classes of ISDN: Basic Rate Interface (BRI) and Primary
Rate Interface (PRI).
- What is a PRI ISDN?
PRI ISDN is designed for organizations with greater
capacity requirements. It uses a full T1 line, transmitting
at 1.544Mbps. It offers 23 B channels at 64Kbps, and
one 64Kbps D (setup) channel.
- What is a BRI ISDN?
Basic ISDN (BRI) is designed to meet the needs of
most individual users and small networks. It is fairly
inexpensive and can use existing phone wiring. It
divides the telephone line into three channels: two
64Kbps bearer channels (B channels) and one 16Kbps
D channel for setting up and managing calls. In some
situations, the two bearer channels can function together
as a single virtual channel, with a data transmission
speed of 128Kbps.
- What is VoIP?
If you've never heard of VoIP, get ready to
change the way you think about long-distance phone
calls. VoIP, or Voice over Internet Protocol,
is a method for taking analog audio signals, like
the kind you hear when you talk on the phone, and
turning them into digital data that can be transmitted
over the Internet.
How is this useful? VoIP can turn a standard
Internet connection into a way to place free phone
calls. The practical upshot of this is that by using
some of the free VoIP software that is available to
make Internet phone calls, you're bypassing the phone
company (and its charges) entirely.
VoIP is a revolutionary technology that has
the potential to completely rework the world's phone
systems. VoIP providers like Vonage have already
been around for a while and are growing steadily.
Major carriers like AT&T are already setting up
VoIP calling plans in several markets around
the United States, and the FCC is looking seriously
at the potential ramifications of VoIP service.
Above all else, VoIP is basically a clever
"reinvention of the wheel." In this article,
we'll explore the principles behind VoIP, its
applications and the potential of this emerging technology,
which will more than likely one day replace the traditional
phone system entirely.
- What is an IP address?
IP Addresses are comparable to telephone numbers.
Just like you would dial a telephone number in order
to call someone, computers use IP Addresses to identify
each other. While phone numbers come in three parts,
IP Addresses come in four parts or octets. Here is
an example:
192.87.35.6
When one computer wants to talk to another it uses
this IP to "call" the other computer.
Static IP address
Most service providers allow you to request or purchase
a static IP address (an IP address that never changes).
With a static IP address you can run various servers
such as your own Web site, FTP site or game server.
- What is a Router?
A router is a common piece of networking equipment
that transmits information between two networks. The
term is commonly used to describe home networking
equipment that connects computers on a local area
network (LAN) and other devices to the Internet using
a single Internet connection. Some common manufacturers
of home routers are Linksys,
Netgear,
and D-Link.
- What is a LAN?
A LAN (local area network) is a group of computers
and network devices connected together, usually within
the same building. By definition, the connections
must be high speed and relatively inexpensive (e.g.,
token ring or Ethernet).
- What is a MAN?
A MAN (metropolitan area network) is a larger network
that usually spans several buildings in the same city
or town.
- What is a WAN?
The wide area network, often referred to as a WAN,
is a communications network that makes use of existing
technology to connect local computer networks into
a larger working network that may cover both national
and international locations. This is in contrast to
both the local area network and the metropolitan area
network, which provides communication within a restricted
geographic area. Here is how the wide area network
functions, and why it is so important to communications
today.
- What is WiMax?
WiMAX is a wireless digital communications system,
also known as IEEE 802.16, that is intended for wireless
"metropolitan area networks". WiMAX can
provide broadband wireless access (BWA) up to 30 miles
(50 km) for fixed stations, and 3 - 10 miles (5 -
15 km) for mobile stations. In contrast, the WiFi/802.11
wireless local area network standard is limited in
most cases to only 100 - 300 feet (30 - 100m).
- What is a Data Network?
The most simplistic definition for a data network
is an electronic communications process that allows
for the orderly transmission and receptive of data,
such as letters, spreadsheets, and other types of
documents. What sets the data network apart from other
forms of communication, such as an audio network,
is that the data network is configured to transmit
data only. This is in contrast to the audio or voice
network, which is often employed for both voice communications
and the transmission of data such as a facsimile transmission.
- What is ADSL?
ADSL (Asymmetric Digital Subscriber Line, or DSL for
short) is a high-speed Internet access service that
utilizes existing copper telephones lines to send
and receive data at speeds that far exceed conventional
dial-up modems.
The fastest dial-up modems are rated at 57 kilobits
per second (Kbps), and usually operate at about 53
Kbps under good conditions. By comparison,
ADSL allows datastream speeds from 1.5 to 8 megabits
per second (Mbps), depending on the grade of ADSL
service purchased.
ADSL uses standard telephone lines to transmit upstream
and downstream data on a digital frequency, which
sets these datastreams apart from the analog signals
telephones and fax machines use. Because the ADSL
signal is operating on a different frequency, the
telephone can be used normally, even when surfing
the Web with ADSL service. The only requirement will
probably be inexpensive DSL filters on each phone
or fax line, to remove any "white noise"
on the line that might be generated from ADSL service.
The "asymmetric" in ADSL refers to the fact
that the downstream data rate, or the data coming
to your computer from the Internet, is traveling faster
than upstream data, or the data traveling from your
computer to the Internet. Upstream data rates are
slower because Web page requests are fairly miniscule
data strings that do not require much bandwidth to
handle efficiently.
- What is SDSL?
SDSL (Symmetric Digital Subscriber Line) is high-speed
Internet access service with matching upstream and
downstream data rates. That is, data can be sent to
the Internet from the client machine or received from
the Internet with equal bandwidth availability in
both directions. Normally, DSL service is asymmetrical
(ADSL), with the bulk of the bandwidth reserved for
receiving data, not sending it.
SDSL is normally used by businesses with a Web presence,
VPN, extranet or intranet needs. In these cases the
client server may be required to upload large streams
of data to the Internet on a regular basis. ADSL would
be slow and inadequate for this purpose, as the bandwidth
available for uploading is normally less than 1 megabit
per second (mbps). SDSL bandwidth can be as high as
7 mbps in both directions.
An Internet service provider offering SDSL may offer
different grades for varying prices. The faster the
data rate, the more expensive the service. Usually,
long-term contracts are required for SDSL service
regardless of the grade chosen.
SDSL utilizes a digital frequency traveling across
existing copper telephones lines to send and receive
data. When using the telephone line for SDSL service,
phone and fax services on that line must be suspended.
Therefore a dedicated second, or additional, line
is needed for SDSL service. This differs from ADSL,
which "leaves room" for both standard analog
telephone equipment and the digital signal, so that
one can talk on the phone or use a fax machine while
online.
SDSL service is an "always on" service,
meaning that the computer is actively connected to
the Internet whenever powered up. If the computer
always remains on, the Internet connection will be
continuously active.
SDSL service requires an SDSL modem, normally supplied
by the Internet service provider, and SDSL equipment
is often proprietary. The SDSL modem will likely require
same-vendor equipment in the LAN, or common DSL chipsets.
Apart from businesses, SDSL can also serve individuals
that require high upload speeds. Network sharing,
for example, has become very popular, and with it
the need for uploading programs and files -- often
extremely large files. SDSL is a good choice for heavy
network sharing, as long as the user has a second
telephone line to dedicate to the service or chooses
to suspend telephone services while online.
SDSL is not available in all areas and speeds might
vary depending upon your physical distance from local
hubs. SDSL service is also more expensive than ADSL,
but well worth the difference for those with demanding
upstream needs.
- What is a Firewall?
A firewall is a system designed to prevent unauthorized
access to or from a private network. You can implement
a firewall in either hardware or software form, or
a combination of both. Firewalls prevent unauthorized
Internet users from accessing private networks connected
to the Internet, especially intranets. All messages
entering or leaving the intranet (i.e., the local
network to which you are connected) must pass through
the firewall, which examines each message and blocks
those that do not meet the specified security criteria.
Several types of firewall techniques exist:
- What is a DMZ?
A Demilitarized Zone or DMZ is a network segment that
is separated from other networks. Many organizations
will use a DMZ to separate their Local Area Networks
(LANs) from the Internet to put additional security
between their corporate network and the public Internet.
Common items to be placed in a DMZ are public facing
servers. For example, if an organization maintains
their website on a server, that web server could be
placed in the DMZ. This way if the machine would ever
be compromised, the remainder of the company's network
is not in danger.
When connecting a LAN to the Internet, a router will
provide the physical connection to the public Internet,
and a firewall will provide a gateway to prevent malicious
data from entering the network. One port on the firewall
will connect to the corporate network using an internal
address on that network, allowing traffic being sent
out by individuals within the company to reach the
Internet. Another port will be configured with a public
address which will allow Internet traffic to reach
the organization. These two ports will allow inbound
and outbound data to reach an organization on the
Internet.
- What is SIP?
SIP stands for Session Initiation Protocol. It is
an application-layer, transport-independent signaling
protocol used to create, modify, and terminate sessions
with one or more participants. It is widely used as
the signaling protocol for Voice over IP. It provides
two-party, multi-party, or multi-cast sessions that
includes instant messaging, Internet telephone calls,
multimedia distribution, and multimedia conferences.
SIP typically operates over TCP port 5060. When encrypted
using TLS, it often uses TCP port 5061.
The basics of VPN A virtual private network (VPN)
allows you to temporarily create or join a private
network across an existing public network by creating
an encrypted tunnel between two hosts (computers).
The tunnel allows you to transfer information securely
and to access remote resources.
- What is MPLS?
MPLS refers to the technological operation that is
more properly known as multi-protocol label switching.
Essentially, MPLS is an operating scheme that is used
to speed up the flow of traffic on a network by making
better use of available network paths. The main thrust
of the idea is to define or designate the proper path
for each function so that the opportunity for bottlenecks
within the network are minimized.
The concept of MPLS was the brainchild of the Internet
Engineering Task Force, or IETF. As the need for handling
more traffic on networks connected to the Internet
became apparent, the concept of establishing labels
in packets that would control the flow and destination
of data was understood to be a solution to the issue.
MPLS made good use of the existing technology and
has continued to be refined as use of the World Wide
Web has continued to grow.
MPLS plays a major role in keeping the networks of
big businesses running smoothly today. The labeling
process involves setting the criteria for information
retrieval, sometimes determined by an IP address.
The data is then directed through routers that have
been pre-determined by the label switching. As a final
step, the data is delivered to the end location. This
entire process is completed in less than a few seconds,
when the system is working at maximum efficiency.
The implementation of MPLS protocols also help make
it possible to run different types of traffic on the
same network, such as the ability to carry data, audio,
and video at the same time. MPLS technology also makes
it possible to restore data faster after a network
failure takes place, even if there is not a backup
server involved in the overall network design. Overall,
MPLS is an essential traffic management tool that
becomes increasingly important as the Internet is
used for more communication applications.
- What is Network Latency?
Network latency is simply defined as the time delay
observed as data transmits from one point to another.
Usually, to determine network latency, the origin
and destination points are used. In some cases, network
latency may be defined by the time it takes some form
of data to make a full circuit back to the originating
point.
While it may seem counterproductive to use the round-trip
time, it actually can be a much better measure of
overall network performance. This is because computers
in the process of sending and receiving bytes are
in constant communication with each other. Even the
one receiving will send information back to the sending
machine. Therefore, network latency can easily be
determined by the round trip time.
- What is Ping?
Ping is a program that sends a series of packets over
a network or the Internet to a specific computer in
order to generate a response from that computer. The
other computer responds with an acknowledgment that
it received the packets. Ping was created to verify
whether a specific computer on a network or the Internet
exists and is connected. The most common way to ping
from a Microsoft operating system >click start>run>type
CMD and press enter. Type the word ping in the
command prompt followed by a space then (www.yahoo.com
or the IP Address you are trying to ping 192.168.1.2)
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