Internet telephony refers to communications services like voice, facsimile, and/or voice-messaging applications—that are transported via the Internet, rather than the public switched telephone network (PSTN).
The basic steps involved in originating an Internet telephony call are conversion of the analog voice signal to digital format and compression / translation of the signal into Internet protocol (IP) packets for transmission over the Internet; the process is reversed at the receiving end. Internet Telephony is a general term for technologies that use the Internet Protocol's packet-switched connections to exchange voice, fax, video and other forms of information. Internet Telephony converges voice, video and data, effectively collapsing three networks into one. To date, however, Internet telephony does not offer the same quality of telephone service as direct telephone connections.
Internet Telephony utilizes established data communication networks to provide telephone services between users. The user phone (or multimedia package on a PC) is attached to a specialized Digital Signal Processing (DSP) device where the voice signal is converted into data packets. Special software on the conversion device translates the destination phone number into an IP address, attaches the appropriate IP header information to the packet, and forwards it to the nearest IP data router to be forwarded to the destination address. The destination system utilizes its DSP to convert the data packets into a voice signal that can be heard on a regular phone receiver or PC speakers.
There are three different ways to place a call using Internet Telephony -
ATA – The most common way to place a telephone way using Internet Telephony is ATA. ATA stands for analog telephone adapter; and it takes the analog signals from your phone and converts it to digital data ready for transmission over the Internet. ATA allows you to connect a standard telephone device to your computer for use with Internet Telephony. You need special software to make it work, but overall is very easy to use.
IP Phones – IP phones look and function just like your ordinary everyday phones but instead of routing your phones through the PSTN lines they route your calls through the Internet Protocol.
Computer to computer – This is by far the simplest way to use Internet Telephony. All you need are special software programs that can route your calls. There are many software available that you can use to many calls directly using your Computer. Other than the software you need a microphone, speakers, sound card and a fast Internet connection.
There are many internet telephony books, VoIP tutorials and VoIP books available that will guide you or you may just browse the internet and search for VoIP comparisons or VoIP reviews before you may any investment in Internet Telephony software or hardware.
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