subject: Cordless Phones Behind The Curtain [print this page] Nowadays it seems that radio technology can be found in a variety of household appliances, including your microwave, your baby monitor, your wireless Internet, and of course your cordless telephone. Despite the fact that the telephone has been around since 1876 - when Alexander Graham Bell first uttered those now famous words Mr Watson come here I want to see you - it was not until 1965 that a jazz singer called Teri Pall, who no doubt saw the advantages of being able to move freely with a wireless handset, first introduced the cordless telephone.
Initially the wireless telephone was only capable of operating on low frequencies, and this meant that they were quite susceptible to interference from other devices that were transmitting radio waves. However, it was not long until models that operated on higher frequencies came about; these were capable of transmitting signals across large distances and without interference.
But how does the technology of the cordless telephone and the corded telephone compare? Well a traditional corded telephone relies on acoustics to transmit an analogue signal back and forth between the caller and the receiver. The hook connects the user to the phone network and the sound is converted through a microphone and speaker. There is also a dial and a bell for dialling and receiving calls; on modern phones this is usually replaced with an electric keypad and ring tone. The most important difference between a corded phone and a cordless phone is the fact that a cordless phone transmits the signals using radio waves, removing the need for the wire.
With a corded phone the signals are converted into radio waves with frequencies, this is done using quartz crystals. These signals are then broadcast using an antenna and boosted using an amplifier. To enable the user to speak and listen at the same time a two-way frequency is used. Also when the phone rings a signal is sent to both the base and the hand set to ensure that the phone would be heard no matter where it is.
Besides the radio technology cordless telephones now have a variety of features that are available, including the caller ID, speed dial, SMS messaging, illuminated keypads and different ring tones. Some models even detect when it is night-time and reduce their ring tone volume accordingly. Most models have LED lights incorporated into them that warn the user if the phone is going out of range or running low on battery life.
