Cordless Telephone Information
Cordless phones allow users to walk around their homes while talking on the phone. They are now so affordable and widespread that there are many options when buying one.
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History
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When cordless phones were first introduced in the 1980s, they were expensive and suffered from several problems, including poor sound quality and an unsecured connection. Over the years, several new technologies have made cordless phones much more useful. Modern cordless phone conversations are almost as difficult to intercept as corded phone conversations, and sound quality is on par with corded phones as well.
Basics
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All cordless phones have two components: The base remains in one place and connects directly to the wall telephone jack; the handset has a speaker, microphone and radio to connect to the base. The phone call comes into the base and is routed to the handset through a radio link. The main differences between cordless phones lie in the different radio technologies that they use to communicate between the handset and the base.
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Radio Technologies
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When cordless phones were first introduced, they operated at a frequency of 27 MHz. As time passed, they began using the 47 to 49 MHz range, expanded to the 43 to 50 MHz range, and eventually operated on the 900 MHz range. Now, only the most basic phones use 900 MHz technology. The use of the 2.4 GHz spectrum is much more common, although this can interfere with common Wi-Fi home networking equipment and microwave ovens. The 5.8 GHz cordless phones are also very common. The newest technology is DECT 6.0, which does not interfere with any other devices and provides very clear audio.
Digital Spread Spectrum
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One of the biggest problems with early cordless phones was that the audio streams between the handset and base could be intercepted by a third party. Digital Spread Spectrum was introduced in 1995 to correct this problem; it allows phones to break up the audio stream into several components and transmit each on a different frequency. This made eavesdropping virtually impossible.
Multi-Handset Systems
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Modern cordless telephones allow users to connect just one base to the phone jack and have several other handset/base modules added to the system without connecting any of the other bases to a phone jack. This is an economical system, and reduces the hassle of finding a phone jack in every room of a house. However, each base must be within the range of the master base station or call quality can be affected.
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References
- Photo Credit wireless phone image by Christopher Dodge from Fotolia.com
