Understanding Digital Telephone Systems

You are likely to encounter three main types of digital telephone systems in the world of business today. A fixed digital telephone system is connected to the main telephone network via cables. Cellular telephones use digital signals sent as radio waves. Voice over Internet Protocol (VoIP) systems utilize the Internet to send and receive voice communications. Knowing how these various systems work can help you wisely choose and deploy the right telecommunications equipment for your company.

Old-style analog telephones work by converting the sound of a voice into an electrical waveform. Digital telephony uses digital information and sound is represented by a series of ones and zeros. Among the advantages of digital telephony are greater bandwidth (the ability to send more information at once) and a lower error rate. Digital phone calls are clearer than calls made using analog phone networks, also known as Plain Old Telephone Systems or POTS.

Most domestic telephone systems and those in small offices are still using analog POTS networks. Digital phone lines are primarily deployed in large networks used for corporate phone systems. Most core digital telephone networks now rely on fiber optics, reports Andrew Wheen in his book "Dot-Dash to Dot.Com." Instead of electricity sent along metal cables, a fiber optic system transmits pulses of light through very fine glass fibers. With a fixed telephone system, your phone must be connected to the network via a cable. With cordless phones, the base must be connected to the network via a cable. Care must be taken not to connect analog telephone equipment to digital phone systems as damage to the equipment can result.

Instead of electrical cables or fiber optics, cellular phone systems use radio signals to transmit digital information. As with other telephones, a small microphone picks up the caller's voice and converts it into a stream of digital information. This information is relayed via radio signals to a receiver, which sends the digital information on to the recipient's phone. Each cellular network controls a certain range of radio frequencies, and each phone has a unique frequency, which prevents other cellular users from accidentally receiving calls meant for other phones.

Voice over Internet Protocol is another form of digital telephony that has become very popular. With VoIP technology, you make digital voice and video calls via the Internet. An example of a VoIP service is Skype. Typically, the caller will wear a headset consisting of headphones and a microphone to make VoIP calls. The caller's voice is picked up by the microphone and converted into a stream of digital information, which is then sent across the Internet to the person receiving the call. The receiver may get the call on his own computer, on a fixed phone line or on a cell phone. VoIP technology can benefit your business by allowing you to make very cheap -- and sometimes even free -- calls.