Internet Telephony

Net 2 phone, PC to PC and PC to phone are many terms that have been used in the past. Later terminology is internet phone, internet telephony, IP telephone and VoIP. Terminology is just a way of concentrating and idea or concept into a few alphabets or words.

The basic thing is you need to communicate and internet telephone is a means of communication using the cables/lines that the internet uses to transfer data. In other words it is running a voice communication over a data network. This leads to a convergence of technologies as the network is now catering to data, voice and even video. The Precursor to internet telephony service is ISDN-Integrated Services Digital Network, which is derived from the German "Integriertes Sprach- und Datennetz" and means "integrated voice and data net". The Present scenario presents us a need to transmit three formats of information

Audio
Video
Stored Data in the form of files

In the past the medium of communication treated these as separate formats and communication systems were developed for these separately. Now days a single communication system that can be useful for all the three formats is available in the form of the computer and so the search is on for a medium that can transmit all three simultaneously.

Internet Telephony

Internet traditionally had been a means of sharing files over a network. Electronic-mail service made it popular to the masses. The network of lines spread rapidly through the world enveloping a whole lot of business and personal communication. Soon voice files and video files were being transferred through the internet. The transfer was slow in the beginning and methods to speed up transfer were soon developed. With faster data rates, the idea of real time communication soon took root.

Internet Telephone was conceived using Internet Protocol as a process for routing the packets. The main advantage is the cost factor which is quite less when compared to using a dedicated PSTN connection. The issues that restrain is inappropriate infrastructure of internet for real time process, call quality and cost of equipment for transmitter and receiver. So far PC seems to be the most used equipment for VoIP. Manufacturers are targeting VoIP as a segment for enormous growth. Internet Telephones and connectors for ordinary phones to the net are the products that aim to capture the imagination of plain old telephone system users.

The major reason why companies go for VoIP is for an integration of its communication system thus reducing overhead costs and paper work. Broadband connections, Quality voice transmission along with encryption and unified messaging is desirable and VoIP is a good starting point.

Telephone Systems

Recounting history, we come to know that the first intelligible telephone call occurred on March 6, 1876, when Alexander Graham Bell, in one room, called to his assistant in another room. "Come here, Watson, I want you." A receiver connected to the transmitter that Bell had designed. This invention grew into a company called Bell Telephone Company (later AT&T), which is one of the largest telephone companies in the world.

The earliest telephone system was known as an exchange and the first exchange linked New York and Boston in 1883. The exchange had a large switch board. An operator would answer an incoming telephone call and connect it to the party being called.

Almon Strowger in the year 1892 installed the first automatic telephone exchange now called the Strowger exchange. Various modifications to the telephone continued and many inventions added to the phone we now know. Telephone exchanges were being built in various cities and long distance telephony connecting cities were soon being established between private parties.

In 1924 AT&T started long distance telephotography (transmission of pictures over the telephone wire), now known as fax. It was between Cleveland and New York. Telephotography had one major use — sending photos of distant events for use by newspapers

Picture Phone was built in 1956. This would enable you to see the person you are talking to. All the innovations failed to make it popular. It was big in size and expensive. This is now realized using computer systems.

Low cost electronic systems have revolutionized communications to the extent of telephone becoming a mobile gadget. Increasing technological advances are bringing together computers and communication this is taking communication technologies to new heights.

Connecting Systems

Connecting systems is the necessary gadgets between the transmitter and the receiver. Primarily for a two phone system it is the medium that carries the voice converted to an electrical/electromagnetic signal. For more number of phones it is the exchange systems that cause the linkage of two particular phones (transmitter and receiver) as well as the medium. The medium between the transmitter and receiver is varied. It can be wired or wireless.

Wired Communication

Twisted Pair cables is two conducting wires wound around each other. There are specifications such as number of twists per meter to reduce cross talk. The types in this are

Shielded Twisted Pair (STP)
Screened Shielded Twisted Pair (S/STP)
Unshielded Twisted Pair (UTP)
Foiled Twisted Pair (FTP)
Screened Unshielded Twisted Pair (S/UTP)
Screened Foiled Twisted Pair (S/FTP)

Coaxial cable consists of a round conducting wire surrounded by an insulating spacer. This is surrounded by a cylindrical conducting sheath, and a final insulating layer. It is designed to carry high frequency or broadband signals. The types being

hard line cable
Triaxial cable or triax
Twin-axial cable or twinax
'Biaxial cable or biax
Semi-rigid cable

Fiber Optic cable made of a transparent fiber for transmitting light. These are commonly used in telecommunications and have a large bandwidth. Modes that can be used are single/multi mode. The cable types being

Loose-tube cable holds up to 12 fibers per buffer tube with a maximum per cable fiber count of more than 200 fibers.
Single-fiber tight-buffered cables
Multi-fiber tight-buffered cables

Wireless Communication

In old terminology, this is stated as radio receiver. Advances brought wireless telegraph, walkie talkie, pager and the present mobile or cellular phone. The medium cannot be changed and therefore the varied systems that were developed in this category were divided depending upon the frequency of transmitted and received wave forms. Mostly the signals would be in the microwave range.

Continue to : Types of VoIP and Packet Switched Networks

The Technicalities of VOIP Simplified!
The Future of Telephony-VoIP
Wireless VOIP – Is It Really Secure?
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