softphone report
TRANSCRIPT
DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING
MAHARISHI ARVIND
INSTITUTE OF ENGINEERING AND TECHNOLOGY
ACKNOWLEDGMENT
A scholarly and quality work like studying any seminar topic can be accomplished by
motivation guidance and inspiration of certain quarters besides the individual efforts. Let
us in this page express our heartiest gratitude to all those who helped us in various stages
In this seminar report.
During our seminar period all the staff member of Deptt. Have helped us with their
skills. Also we are thankful to other technical staff of the Deptt. who have helped us to
complete our report successfully. We Wish to express our deep sense of gratitude to our
seminar guide “Mr. Lokesh Sharma” for his valuable guidance and kind cooperation
without which this report would have not been possible.
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Maharishi Arvind Institute of Engineering & Technology (Approved by AICTE and Affiliated to Rajasthan TechnicalUniversity,Kota) Sector7, Madhyam Marg, Mansarovar, Jaipur-302020, Rajasthan, India Department of Electronics & Communication Engineering.
Certificate
This is to certify that the Seminar report entitled “SOFTPHONES” being submitted by NIMISHA BHATNAGAR is a bonafide record of project work carried out by him under my supervision and guidance, and hence approved for submission to the Department of Electronics & Communication Engineering in partial fulfilment of the requirements for the award of the degree of Bachelor of Technology in Electronics & Communication Engineering of the Rajasthan Technical University Kota, Rajasthan during the academic year 2011-2012.
Mr. Lokesh Sharma Mr. K.K. Bhargava Lect. & Project Guide Associate Professor& Head of the Dept.
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INDEX
SOFTPHONES
COMMUNICATION PROTOCOLS
CIRCUIT SWITCHING vs. PACKET SWITCHING
SOFTSWITCH
IP TELEPHONY
IP ADDRESSES AND NAMES
ROUTERS AND ROUTING
SESSION INITIATION PROTOCOL (SIP)
ADVANTAGES OF SOFTPHONES
DISADVANTAGES OF SOFTPHONES
VoIP BASED SOFTPHONES
CONCLUSION
REFERENCES
SOFTPHONES4
Introduction:
A softphone is a software program for making telephone calls over the Internet using a
general purpose computer, rather than using dedicated hardware. Often a softphone is
designed to behave like a traditional telephone, sometimes appearing as an image of a phone,
with a display panel and buttons with which the user can interact. A softphone is usually used
with a headset connected to the sound card of the PC, or with a USB phone.
A VoIP softphone enables you to make calls with just your computer using a VoIP service.
How soft phone works is very similar to a regular telephone. The only difference is that it is
found in our computer.
How It Works:
We can download soft phones or it may be part of the VOIP package. Regardless, a soft
phone may look like a regular telephone in your PC. If we want to use it, we may need to
open a window, press the shortcut key in your keyboard, or open a program where it’s
currently embedded.
If we need to talk to someone, make sure that we are wearing our headset and the microphone
is on. Soft phones can be used for any type of calls, from PC to PC as well as from phone line
to PC and vice versa.
Requirements:
To make voice calls over the Internet, a user typically requires the following:
A modern PC with a microphone and speaker, or with a headset, or with USB phone.
Reliable high-speed Internet connectivity like Digital subscriber line (DSL) or cable
service.
Account with an Internet telephony service provider or IP PBX provider.
Who Can Benefit From VoIP Softphones?
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Softphones can be used by anybody with a computer. There are a few types of users who can
really benefit from the features of a VoIP softphone:
VoIP beginners
Heavy travelers
Telecommuters
Call centre employees
Small businesses
Frequent long-distance callers
VoIP beginners can quickly and cheaply explore how the service works by downloading a
VoIP softphone to make free computer-to-computer or computer-to-phone calls. Heavy
travellers can avoid racking up large bills on their mobile phones or at hotels by using a low-
cost VoIP service with a VoIP softphone. Telecommuters can register a VoIP softphone with
their office PBX system to enjoy the same call features available to them at the office while
they are on the move. Call centre employees and small businesses can save on costs by
pairing a VoIP service with a softphone to avoid purchasing and maintaining desk phones.
International and long-distance rates are much lower when using a VoIP softphone, so those
making regular or frequent calls out-of-state or country can cut some major costs.
VoIP Softphone Features:
VoIP softphones offer the same features that traditional phones offer and more:
Call forwarding.
Call conferencing.
Hold capabilities.
Call transferring.
Voicemail.
Greeting capabilities.
Text, IM, and video capabilities.
Echo cancellation to improve sound quality.
Contact list/address book.
Communication Protocols:
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Voice over Internet Protocol(VoIP) :
Voice over IP (VoIP) commonly refers to the communication protocols, technologies,
methodologies, and transmission techniques involved in the delivery of voice
communications and multimedia sessions over Internet Protocol (IP) networks, such as
the Internet. Other terms commonly associated with VoIP are IP telephony, Internet
telephony.
Internet telephony refers to communications services —voice, fax, SMS, and/or voice-
messaging applications— that are transported via the Internet, rather than the public switched
telephone network (PSTN). The steps involved in originating a VoIP telephone call are
signalling and media channel setup, digitization of the analog voice signal, encoding,
packetization, and transmission as Internet Protocol (IP) packets over a packet-switched
network. On the receiving side, similar steps (usually in the reverse order) such as reception
of the IP packets, decoding of the packets and digital-to-analog conversion reproduce the
original voice stream.
VoIP is available on many smartphones and Internet devices so that users of portable devices
that are not phones, may place calls or send SMS text messages over 3G or Wi-Fi.
VoIP allows both voice and data communications to be run over a single network, which can
significantly reduce infrastructure costs. VoIP devices have simple, intuitive user interfaces,
so users can often make simple system configuration changes. Dual-mode phones enable
users to continue their conversations as they move between an outside cellular service and an
internal Wi-Fi network, so that it is no longer necessary to carry both a desktop phone and a
cell phone.
Session Initiation Protocol (SIP):
The Session Initiation Protocol (SIP) is an IETF-defined signalling protocol widely used for
controlling communication sessions such as voice and video calls over Internet Protocol (IP).
The protocol can be used for creating, modifying and terminating two-party (unicast) or
multiparty (multicast) sessions. Sessions may consist of one or several media streams.
Other SIP applications include video conferencing, streaming multimedia distribution, instant
messaging, presence information, file transfer and online games.
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How VoIP Works?
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.
The interesting thing about VoIP is that there is not just one way to place a call. There are
three different "flavors" of VoIP service in common use today:
ATA -- The simplest and most common way is through the use of a device called
an ATA (analog telephone adaptor). The ATA allows you to connect a standard
phone to your computer or your Internet connection for use with VoIP. The ATA is
an analog-to-digital converter. It takes the analog signal from your traditional
phone and converts it into digital data for transmission over the Internet. Providers
like Vonage and AT&T Call Vantage are bundling ATAs free with their service.
You simply crack the ATA out of the box, plug the cable from your phone that
would normally go in the wall socket into the ATA, and you're ready to make VoIP
calls. Some ATAs may ship with additional software that is loaded onto the host
computer to configure it; but in any case, it's a very straightforward setup.
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IP Phones -- These specialized phones look just like normal phones with a
handset, cradle and buttons. But instead of having the standard RJ-11 phone
connectors, IP phones have an RJ-45Ethernet connector. IP phones connect directly
to your router and have all the hardware and software necessary right onboard to
handle the IP call. Wi-Fi phones allow subscribing callers to make VoIP calls from
any Wi-Fi hot spot.
Computer-to-computer -- This is certainly the easiest way to use VoIP. You don't
even have to pay for long-distance calls. There are several companies offering free
or very low-cost software that you can use for this type of VoIP. All you need is
the software, a microphone, speakers, a sound card and an Internet connection,
preferably a fast one like you would get through a cable or DSL modem. Except for
your normal monthly ISP fee, there is usually no charge for computer-to-computer
calls, no matter the distance.
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Circuit Switching Vs Packet Switching:
Existing phone systems are driven by a very reliable but somewhat inefficient method for
connecting calls called circuit switching.
Circuit switching is a very basic concept that has been used by telephone networks for more
than 100 years. When a call is made between two parties, the connection is maintained for the
duration of the call. Because you're connecting two points in both directions, the connection
is called a circuit. This is the foundation of the Public Switched Telephone Network (PSTN).
The important thing to look for in transmitting information over such a complex network is
the path or circuit. The devices making up the path are called nodes. For instance, switches,
routers and some other network devices are nodes.
In circuit-switching, this path is decided upon before the data transmission starts. The system
decides on which route to follow, based on a resource-optimizing algorithm, and transmission
goes according to the path. For the whole length of the communication session between the
two communicating bodies, the route is dedicated and exclusive, and released only when the
session terminates.
In Circuit Switching networks, when establishing a call a set of resources is allocated for this
call. These resources are dedicated for this call, and can be used by any of the other calls.
Circuit Switching is ideal when data must be transmitted quickly, must arrive in sequencing
order and at a constant arrival rate. There for when transmitting real time data, such as audio
and video, Circuit Switching networks will be used.
Packets:
To be able to understand packet-switching, you need to know what a packet is. The Internet
Protocol (IP), just like many other protocols, breaks data into chunks and wraps the chunks
into structures called packets. Each packet contains, along with the data load, information
about the IP address of the source and the destination nodes, sequence numbers and some
other control information. A packet can also be called a segment or datagram.
Once they reach their destination, the packets are reassembled to make up the original data
again. It is therefore obvious that, to transmit data in packets, it has to be digital data.
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In packet-switching, the packets are sent towards the destination irrespective of each other.
Each packet has to find its own route to the destination. There is no predetermined path; the
decision as to which node to hop to in the next step is taken only when a node is reached.
Each packet finds its way using the information it carries, such as the source and destination
IP addresses.
Packet switching main difference from Circuit Switching is that that the communication lines
are not dedicated to passing messages from the source to the destination. In Packet Switching,
different messages can use the same network resources within the same time period. Since
network resources are not dedicated to a certain session the protocol avoid from waste of
resources when no data is transmitted in the session. Packet Switching is more efficient and
robust for data that is burst in its nature, and can withstand delays in transmission, such as e-
mail messages, and Web pages.
Consider the two following examples to answer your question:
Example of Circuit Switching:-
You pick up your land phone and dial your friend. At that point, the TELCO provider creates
a dedicated Circuit for that session and connects you to your friend's telephone. No matter
how long you keep the line open with your friend, the circuit will remain, and packets
flowing between both telephones will always follow the same path. This is an example of a
circuit-switched network.
Example of packet-switching:-
In the second example, you switch on your PC and connect to your favorite site that offers a
number of applications you can download from, so you begin downloading one application at
a time. Each packet has to find its own route to the destination, i.e., your computer. Each
packet finds its way using the information it carries, such as the source and destination IP
Address. If network congestion occurs, the routers responsible for routing packet between
networks will automatically select different paths to ensure data is transferred as required.
This is an example of a packet-switched network.
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Soft switch
A softswitch is a central device in a telecommunications network which connects telephone
calls from one phone line to another, typically via the internet, entirely by means of software
running on a general-purpose computer system. Most landline calls are routed by purpose-
built hardware, formerly using physical switchboards, but softswitches are the dominant 21st
century trend.
A softswitch is typically used to control connections at the junction point between circuit-
switched and packet-switched networks. A single device containing both the switching logic
and the switching fabric can be used for this purpose.
Softswitch is the functional component that provides call-related features. Capabilities such
as call forwarding, call waiting, last call return and three way videoconferencing, if
implemented in the network
VoIP Softswitches are subdivided into two classes. Class 4 softswitches and Class 5
softswitches.
Softswitches used for transit VoIP traffic between carriers are usually called class 4
softswitches. Analogous with other Class 4 telephone switches, the main function of the class
4 softswitch is the routing of large volumes of long distance VoIP calls. The most important
characteristics of class 4 softswitch are protocol support and conversion, transcoding, calls
per second rate, average time of one call routing, number of concurrent calls.
Class 5 softswitches are intended for work with end-users. These softswitches are both for
local and long distance telephony services. Class 5 softswitches are characterized by
additional services for end-users.
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IP Telephony:
IP telephony (IPT) offers a viable alternative to the legacy voice exchange, delivering
improved application integration, scalability, and multi-site management. It is precisely these
features that make this rapidly-maturing technology so attractive to organizations seeking to
reduce costs, increase productivity and improve customer relations. However, voice is critical
to business, and a major change to emerging technologies like IPT requires an understanding
of a broad range of technologies, careful planning and thoughtful implementation. This guide
has been compiled to help decision makers to understand the relevant technologies as they
define their strategies.
Fig: 1.1 Network Layout of A small businesses VoIP
Following the introduction, we will review the typical components and features of an
enterprise telephony system. We then introduce voice over IP (VoIP), the underlying network
infrastructure, and then we address the various issues one must take into account when
designing the network to carry voice. We conclude by comparing these VoIP solutions to the
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traditional centralized PBX, but before we do so, we describe advanced applications such as
collaboration, presence, customer relationship management and unified messaging.
There are many reasons to implement an IP-based voice communication system reduced
long-distance telephony charges; lower capital costs; lower management and administrative
costs; reduced complexity; improved integration of distributed business entities; and a greater
ease with which voice applications may be combined with other business systems.
IP ADDRESSES AND NAMES
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2.1. IP (Internet Protocol):
The Internet Protocol (IP) is the principal communications protocol used for relaying
datagrams (also known as network packets) across an internetwork using the Internet
Protocol Suite. Responsible for routing packets across network boundaries, it is the primary
protocol that establishes the Internet.
IP is the primary protocol in the Internet Layer of the Internet Protocol Suite and has the task
of delivering datagrams from the source host to the destination host solely based on
the addresses. For this purpose, IP defines datagram structures that encapsulate the data to be
delivered. It also defines addressing methods that are used to label the datagram source and
destination.
Internet Protocol Suite is sometimes referred to as TCP/IP.
Function:
The Internet Protocol is responsible for addressing hosts and routing datagrams (packets)
from a source host to the destination host across one or more IP networks. For this purpose
the Internet Protocol defines an addressing system that has two functions: identifying hosts
and providing a logical location service. This is accomplished by defining standard datagrams
and a standard addressing system.
Datagram Constuction:
Each datagram has two components, a header and a payload. The IP header is tagged with the
source IP address, destination IP address, and other meta-data needed to route and deliver the
datagram. The payload is the data to be transported. This process of nesting data payloads in
a packet with a header is called encapsulation.
The protocol was needed that could provide an open interface between applications and the
various physical networks underneath (e.g.,, Ethernet on the LAN, Frame Relay, DSL and
ISDN in the WAN, etc..). There have been various proposed protocols including:
1. IP Internetworking Protocol – IETF standard
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2. OSI Open Systems Interconnect – ITU standard
3. IPX Internet Packet exchange – Novell.
IP Addresses:
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IP addresses are used to identify devices connected to the network. The 32-bit addresses are
written as four decimal values (with each group capable of representing less than 256 values)
separate by a dot. The first groups of numbers identify the network upon which the machine
is located, and the other groups of numbers identify the specific machine within that subnet
work. Here is an example: 169.254.70.213
Fig: 2.1 IP Windows
When installing a computer, the network manager defines the machine’s address and the
address of the default gateway – the machine on the local network that provides connectivity
to other networks. In the early days of the Internet, this machine would be a computer with
two network interfaces and it would perform the task of forwarding packets between the two
interfaces. Today however, it is more likely to be a router. For use on machines connected
directly to the Internet, IP addresses are carefully allocated in blocks and managed by the
owner of the addresses to ensure that no two machines have the same address. However,
within an enterprise the IETF has allocated certain address ranges for internal machines only.
The addresses of the internal machines are protected by a firewall that provides Network
Address Translation (NAT) that not only protects the identity of internal machines, but also
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ensures that addresses belonging to one enterprise do not conflict with similar addresses used
by another enterprise.
Like telephone numbers, the numbers to the right of the address identify the specific machine
or device. When planning an IP voice implementation, a legacy voice manager should learn
the details of the addressing scheme used within the organization before connecting new IP
devices to the network. To make it easier for people to find services on their network and on
the Internet, a name-to-number translation service was introduced called the Domain Name
System (DNS). This global system allows one to type in a name like http://www.louvre.fr/
rather than its IP address http://160.92.103.98. The DNS service simplifies things by allowing
the end user to memorize a website name instead of having to remember its IP address, which
could change if the Louvre were to change to a different service provider.
When you consider how you use phone numbers in your cell phone, you will recognize that
here too, you use people’s names rather than their numbers. Later we will show how this
facility is being introduced by the current generation of IP voice systems.
Allocating and Managing Addresses:
Given that each device has to have its own IP address, does this mean that you must manually
assign an IP address to every phone you install on your network? Fortunately, the answer to
this question is “no.”An automatic address allocation system was developed to ease the
administrative overhead associated with IP address allocation: Dynamic Host Configuration
Protocol (DHCP).The DHCP protocol resides on a server and manages a pool of IP
addresses. DHCP keeps track of which addresses are currently in use and which are available
for allocation.
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ROUTERS AND ROUTING
In the telephony world, conversations are carried out over circuits – end to end connections
between the caller and collie. All the work of determining how to route the call is done during
call setup. Once the circuit is in place, no further route decisions are required (assuming there
are no catastrophic problems on the network).Data networks, however, do not work like this.
Packets are forwarded and forgotten so that each intermediary router between the source and
the destination:
1. Reads the destination address of the packet
2. Checks which route to use
3. Forwards the packet to the interface associated with that route
4. And forgets it.
The primary function of a router is to route packets along the best path across a network.
Each router maintains a route table, essentially a roadmap of the network which is kept up to
date by exchanging information with other routers about the status of each link and the status
of the network.
Fig: 4.1 Routing technology
When an incoming packet is received, a router identifies the destination address, checks the
route tables to determine the best route, and then forwards the packet to the next router along
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the path. A router should be connected to multiple forwarding paths so that if one path fails,
packets will be re-routed around the failed connection.
Due to their strategic location in the network (at the LAN/WAN boundary), routers are
frequently used to prioritize and filter traffic. Note that WAN links are shared resources and
therefore suffer from similar contention problems inherent with the early Ethernet. This can
cause serious problems for real-time voice communications.
QoS will be discussed in the following section:
Routers are also used to act as a firewall, filtering packets to protect the network from
unwanted attempts to gain access to the network. Firewalls use techniques similar to traffic
prioritization; that is, they identify and filter traffic based on source or destination address,
protocol type, or IP port numbers. Port and socket numbers, in particular, may indicate
application functions such as telnet or file transfer protocol (FTP), and because these
applications can be used to break into a corporate network, identifying these types of traffic
before the traffic enters the network can offer valuable protection. There are literally
hundreds of well-known techniques for breaking into a network, such as IP spoofing, Denial
of Service attacks, or SYN floods. In all cases, the router or firewall must be capable of
identifying and filtering these types of traffic. Use of traffic prioritization or firewall
technology could become an issue when transporting voice over the network due to the
additional processing required for these functions. However, the newest generation of routers
and stand-alone firewall devices has become much more powerful, making use of custom
ASICs to simultaneously classify, queue, filter, and forward packets with minimal latency.
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SESSION INITIATION PROTOCOL (SIP)
The Session Initiation Protocol (SIP) is an IETF-defined signalling protocol widely used for
controlling communication sessions such as voice and video calls over Internet Protocol (IP).
The protocol can be used for creating, modifying and terminating two-party (unicast) or
multiparty (multicast) sessions. Sessions may consist of one or several media streams.
Other SIP applications include video conferencing, streaming multimedia distribution, instant
messaging, presence information, file transfer and online games.
1. SIP User Agent Clients (UACs)
2. SIP Location Server – track which IP address a client is currently using
3. SIP Proxy Servers – forwards requests to other servers on behalf of SIP clients.
4. Redirect Servers – communicates the target address of the called party to the calling party.
User Agent:
A SIP user agent (UA) is a logical network end-point used to create or receive SIP messages
and thereby manage a SIP session. A SIP UA can perform the role of a User Agent
Client (UAC), which sends SIP requests, and the User Agent Server (UAS), which receives
the requests and returns a SIP response. A SIP phone is a SIP user agent that provides the
traditional call functions of a telephone, such as dial, answer, reject, hold/unhold, and call
transfer. SIP phones may be implemented as a hardware device or as a softphone.
Proxy server:
An intermediary entity that acts as both a server (UAS) and a client (UAC) for the purpose of
making requests on behalf of other clients. A proxy server primarily plays the role of routing,
which means its job is to ensure that a request is sent to another entity "closer" to the targeted
user. Proxies are also useful for enforcing policy (for example, making sure a user is allowed
to make a call). A proxy interprets, and, if necessary, rewrites specific parts of a request
message before forwarding it.
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Registrar:
A server that accepts REGISTER requests and places the information it receives in those
requests into the location service for the domain it handles which registers one or more IP
addresses to a certain SIP URI, indicated by the sip: scheme, although other protocol schemes
are possible. More than one user agent can register at the same URI, with the result that all
registered user agents will receive a call to the SIP URI.
SIP registrars are logical elements, and are commonly co-located with SIP proxies. But it is
also possible and often good for network scalability to place this location service with a
redirect server.
Redirect server:
A user agent server that generates 3xx (Redirection) responses to requests it receives,
directing the client to contact an alternate set of URIs. The redirect server allows proxy
servers to direct SIP session invitations to external domains.
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Advantages of VoIP:
VoIP phone service providers offer many advantages to the residential and small office/home
office user. If you have a high speed internet connection then choosing a VoIP phone service
might be right for you.
Low Cost:
This technology leads to greater financial savings. This happens because there exists only one
network carrying the voice and data provided by only one supplier. If you have a broadband
Internet connection (DSL or cable), you can make PC-to-PC phone calls anywhere in the
world for free. If you wish to make a PC-to-phone connection, there's usually a charge for
this but probably much cheaper than your regular phone service.
You can pay as you go or you can sign up with a VOIP service provider and pay a monthly
fee in return for unlimited calls within a certain geographic area. For example, some VOIP
services in the United States allow you to call anywhere in North America at no extra charge.
Low Taxes:
Since the calls are being carried over the Internet, governments have not heavily taxed VoIP
phone services. Compare that to your local telephone bill (go ahead and take a close look)
and you will see you are spending quite a bit on taxes each month. Therefore, choosing a
VoIP provider could add up to significant savings for you and your family.
Portability:One important concept to understand about VoIP is that unlike it’s forefathers (let’s call them
PSTN for now), it is not distance or location dependent. As far as VoIP is concerned, you
could be calling your supplier 1,000 miles away in Indonesia or calling your business partner
on the other end of town, and it doesn’t make any difference at all, in terms of connectivity.
You can make and receive phone calls wherever there is a broadband connection simply by
signing in to your VoIP account. This makes VoIP as convenient as e-mail – if you are
travelling, simply pack a headset or Internet phone and you can talk to your family or
business associates for almost nothing.
No extra cables, no extra cost:A VoIP phone number, unlike your regular phone number, is completely portable. Most
commonly referred to as a virtual number, you can take it with you anywhere you go.Even if 25
you change your office address to another state, you phone number can go with you. Heck,
you can even take your whole business with you wherever you travel.
Features:Unlike regular phone service which usually charges more for extra features, VOIP comes
with a host of advanced communication features. For example, call forwarding, call waiting,
voicemail, caller ID and three-way calling are some of the many services included with VOIP
telephone service at no extra charge. You can also send data such as pictures and documents
at the same time you are talking on the phone.
VoIP phones can integrate with other services available over the Internet, including video
conversation, message or data file exchange in parallel with the conversation, audio
conferencing, managing address books and passing information about whether others (e.g.
friends or colleagues) are available online to interested parties.
Flexibility:
When you choose a VoIP phone service provider, you will be sent a converter to allow a
regular phone to use the VoIP phone service. Your phone number is programmed into the
converter. This means that you can take your phone converter and phone number and use
them wherever you travel in the world, just as long as you have access to a high-speed
Internet connection. Because your telephone number is based in your converter (and not your
home/office), you have the option of choosing any area code for your phone number. Some
carriers will allow you to have more than 1 phone number in different area codes for a small
additional fee (called a virtual phone number).
Video-conferencing:
VoIP enables advanced bandwidth capabilities and improved video-conferencing and at a
reasonable price.
Disadvantages of VoIP:
If VOIP is starting to sound really good to you, make sure you understand the following
downsides as well.
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No service during a power outage:
During a blackout a regular phone is kept in service by the current supplied through the
phone line. This is not possible with IP phones, so when the power goes out, there is no VOIP
phone service. In order to use VoIP during a power outage, an uninterruptible power supply
or a generator must be installed on the premises. It should be noted that many early adopters
of VoIP are also users of other phone equipment such as PBX and cordless phone bases that
also rely on power not provided by the telephone company.
Emergency calls:
Another major concern with VOIP involves emergency 911 calls. Traditional phone
equipment can trace your location. Emergency calls are diverted to the nearest call center
where the operator can see your location in case you can't talk. However, because a voice-
over-IP call is essentially a transfer of data between two IP addresses, not physical addresses,
with VOIP there is currently no way to determine where your VOIP phone call is originating
from.
Although many companies are making an effort to provide for emergency calls in their
service, this issue remains an important deterrent against VoIP.
Reliability:
Because VOIP relies on an Internet connection, your VOIP service will be affected by the
quality and reliability of your broadband Internet service and sometimes by the limitations of
your PC. Poor Internet connections and congestion can result in garbled or distorted voice
quality. If you are using your computer at the same time as making a computer VOIP call,
you may find that voice quality deteriorates dramatically.
This is more noticeable in highly congested networks and/or where there are long distances
and/or internetworking between end points.
VoIP Voice Quality:
VoIP has a bit to improve on Voice Quality, but not in all cases. VoIP QoS (Quality of
service) depends on so many factors: your broadband connection, your hardware, the service
provided by your provider, the destination of your call etc. More and more people are
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enjoying high quality of phone calls using VoIP, but still many users complain of hearing
Martian, having to wait a lot before hearing an answer etc.
Security:
This one is the last in this list, but it is not the least! Security is a main concern with VoIP, as
it is with other Internet technologies. The most prominent security issues over VoIP are
identity and service theft, viruses and malware, denial of service, spamming, call tampering
and phishing attacks.
Other:
The domestic customers have to use headphone to make and receive phone calls, which
usually international. But this could be changed when analogue telephones will be brought up
to serve the same purpose.
VoIP Based Softphones
VoIP Cheap:
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It is software which we can install in our computers or laptops. Through this we can talk to
anyone in the world at very cheap or rather for free. VOIP soft phones are used by millions of
users worldwide to make voice and video calls. It looks like a traditional telephone. Through
this we can make calls to any landline or mobile network.
People now no more have to think about international call rates. You can talk to your
relatives or for business point of view without thinking about the rates. Just you have to
download software called voipcheap install it and then you can easily talk to anyone like we
do it through our mobiles or landline. The only difference between this and traditional phone
is that it works through the internet.
VoIP Cheap Dialpad:
As we can see in the picture, its keypad looks the same as the traditional phones. We can dial
the number by using the mouse click. It has got many features like we can send sms even
through these softwares. If we are using the same number then we can just add the contact of
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that person in the list so that later on we don’t have to dial the number just by clicking on the
contact name the number will be dialled.
This is the way how we can send messages through this software.
CONCLUSION
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VoIP systems today cannot only match the features of legacy PBXs, but they have been built
with today’s communications environment in mind. When most of the legacy PBX
architectures were launched, the Internet was irrelevant to mainstream business activity.
Today, however, the Internet is a crucial tool in facilitating business, and IP forms the
foundation for many of the applications and systems that continue to drive our productivity to
new levels. IP telephony is inherently designed to leverage the Internet phenomenon,
providing a distributed communications infrastructure that businesses will use to both scale
and simplify their activities simultaneously.
REFERENCES
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