The technology required to make PC to PC calls is similar to making calls with a regular phone. In phone to phone communication, also called analog telephony, three steps are required for communication to occur. In the first step, the sounds of your speech must be converted by the telephone into waves of electrons. These electron waves are analogous to the sound waves you emit with your mouth, hence the term ‘analog’. In the second step, these electronic waveforms must be transmitted over a telephone cable, through a series of switches, to the receiving telephone. In the third step, the receiving telephone must convert the analog waves back into sound.
Making PC to PC calls, also called ‘IP telephony’, requires that the computer convert the sound waves of your speech into digital representations of the sounds. IP telephony must also transmit those digital representations along a cable, and the receiving computer must convert the digital representations back into sound. Aside from using a different device, a computer, instead of a phone, the significant difference between analog telephony and IP telephony is the manner in which the sounds of your voice are represented. In IP telephony, your sounds are coded into digital representations of the sounds you make, and these digital representations are converted to analog audio by the receiving computer. Since IP telephony encodes the sound, a code key is required. These keys are called audio codecs. A digital representation of a sound means a specific number is assigned to that sound.
To conduct a PC to PC call, like a phone, your computer and the computer you call will need a microphone and speaker. This means your computer must be equipped with a sound board. If you can play music on your PC, you have a sound board. In addition, you’ll need software that emulates a phone. This will be a program that displays a phone image, with buttons for numbers, for initiating the dial, for receiving a call and other similar phone functions. This software is often called a ’softphone’.
Of course, your computer will also have to be connected to the Internet and will have to connect through the Internet to a server that will control the PC to PC call setup and the signaling between senders and receivers. These servers implement a PC to PC protocol called the ‘Session Initiation Protocol’, or SIP. There are many SIP providers available today, some offering free PC to PC call services. Others offer PC to phone service by charge. Still, others provide both free PC to PC call and PC to phone call services for free and rely on advertising to make a profit.
Getting started is easy and quick. For example, the Yahoo Messenger can be downloaded for free. After it is installed, you add a contact and you simply click on a call button to initiate the call. Google provides free PC to PC calls with its Google Talk client. Skype is one of the more popular SIP providers and many others are appearing on the scene with free PC to PC call services and low PC to phone call prices that out price traditional telephone companies.
IP telephony is now preferred to the plain old telephone system, if for no other reason than that PC to PC call services are free. This is because the Internet imposes no charges on the user for connections made anywhere in the world. The flat fee you pay your Internet provider is the only associated cost. As long as the Internet continues this policy, these services will be the preferred telephony method for people and businesses wanting to keep their voice communications cost low. Have parents in another state, children spread all over the country? Start using IP telephony and save big bucks on staying connected to those you care about.