In simple terms, a cordless phone consists of a base unit, and at least one handset, which communicate with each other via RF (`Radio Frequency`) waves, rather than a physical wire, or cord. DECT, or `Digital Enhanced Cordless Telecommunications`, is a standard for digital cordless telephone equipment in the UK and Europe. Digital cordless phones of this type are far superior to their analogue predecessors in a number of ways. Most analogue cordless phones operate on a limited number of frequencies, so interference from other phone equipment is a common problem; digital cordless phones complying with the DECT standard, on the other hand, operate on 120 channels, so interference is never a problem. Digital cordless phones also have a greater range, that is, the distance from a base unit that they can be used, up to a maximum of roughly 1,000 feet.
Cordless Digital Phone Features
A cordless handset obviously requires a power source of some kind, and power is usually supplied by rechargeable batteries of the Lithium ion (`Li-Ion`), Nickel Metal Hydride (`NiMH`) or Nickel Cadmium (`NiCad`) type. Li-Ion batteries offer roughly 40% more storage capacity than NiMH batteries – which, in turn, offer 33% more capacity than NiCad batteries of the same size – and are less susceptible to the so-called `memory effect`. They are, however, more expensive than the other rechargeable battery types.
With regard to frequencies, so-called `third generation`, 2.4 GHz cordless phones share the frequencies between 2.4 and 2.4835 GHz with 802.11b and 802.11g wireless networks, while `fourth generation`, 5.8GHz phones share the frequencies between 5.725 and 5.850 GHz with 802.11a wireless networks. Some 5.8 GHz phones only use the higher frequency band to transmit from a base unit to a handset, and use 2.4 GHz in the reverse direction, to prolong the life of handset batteries.
In terms of the actual operation of a cordless digital phone, provided that you have `caller ID` as part of a package from your telephone service provider, the number – and the name, if you have previously saved this information – associated with an incoming call will be displayed on the LCD (`Liquid Crystal Display`) screen on the handset. Similarly, `call waiting` allows you to see the details of a second incoming call, while you are talking to the first caller. The Philips DECT 6231 Cordless Digital Phone, for example, has a backlit display, capable of displaying 4,096 colours, and caller ID display.
The latest cordless digital phones have integral speakers in the handset, or the base unit, or both, which allow you to talk on the phone, completely hands-free. Full duplex operation allows you and your caller to speak freely, and simultaneously, without any information being lost. Most models also include a `mute`, or `privacy` button, which can be useful in a business, or domestic, setting when you want to talk to someone other than the person on the other end of the phone, or you simply want to carry on a conversation while `holding` on the phone. The Doro 635IPW Cordless Digital Phone, for example, includes loudspeakers and hands free functionality.
If you need to be able to pick up calls to more than one telephone number, from the same handset, cordless digital phones are available with the capability of receiving calls on two, four, or even as many as 12, separate telephone lines.