Cordless wall phones are phones that have wireless handsets connected to bases with landline connections. Unlike mobile phones, cordless wall phones must be used in close proximity to the base. Cordless wall phones come in a variety of frequency ranges. The most common range is from 900 MHz, to 2.4 GHz, to 5.8 GHz. Cordless wall phones may be attached by a mounting base to the wall or the base may simply have cord plugged into the wall.
While the choices may seem somewhat confusing at first, cordless wall phones operating at higher frequencies offer some advantages. For example, a cordless wall phone at 5.8 GHz has less of a chance of being interfered with by other wireless devices, such as radios, wireless computer networks, and other such signals. Therefore, some consider the higher frequencies to be very important when considering cordless wall phones.
Higher frequencies often mean greater ranges as well, though there is more to the range of a cordless phone than just one factor. Still, a 5.8 GHz cordless wall phone may be able to go as far as 2,000 feet (0.6 km) and still be able to communicate with the base. Generally, cordless wall phones will never be taken this far from their bases.
There is a disadvantage to those higher frequencies as well. Transmitting signals at higher frequencies requires greater amounts of power, meaning that the battery life of a cordless wall phone is diminished at higher frequencies. Still, for those who make sure their phones are recharged frequently, this should not be a major problem.
Cordless wall phones at the 5.8 GHz range may also not transmit totally at that range. Some phones have a 5.8 GHz transmission from the base to the handset only. Transmissions from the handset to the base operate at the more common 2.4 GHz. This helps conserve battery life but may not be acceptable to those who demand a true 5.8 GHz transmission. These types of phones are called dual transmission phones.
While the basic technology behind cordless wall phones has not changed much over time, there have been some improvements. For example, spread spectrum technologies have made it harder for others to listen in on private conversations that may be in range of other types of receivers, such as radio scanners. Also, the frequency ranges have gone from under 50 MHz to the current maximum of 5.8 GHz. Still, the basic function of the phone has not changed much at all.