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Buying Cordless Phones: Frequencies 101

by Liz Pedro

Do you remember when cordless phones first came out in the eighties? I do and I remember two things about them. One is that they were pretty expensive and the other is there were only a few models to choose from. A lot has changed in the past twenty years. Now not only are there many models to choose from, but you need to choose a phone frequency too. You can choose from 5.8 GHz, 2.4 GHz, 900 MHz or the new DECT technology.

Do frequencies matter? And if they do, how much do they matter? Most people assume the higher the frequency is, the better the cordless phone must be. The goal of this article is to provide some information to help you decide which cordless phone is right for your home or office.

Traffic and Interference

Before you pick a phone, you need to consider some important factors. The first factor to consider is traffic. The Federal Communications Commission (FCC) assigns a specific range of frequencies that are used by cordless phones. Since devices such as cell phones are also transmitting and receiving wireless signals sometimes there is interference. To prevent this type of interference, the FCC determines which devices can transmit within specific ranges. When a range reaches capacity, the FCC will usually open up another range of frequencies.

The early cordless phones used 46-49 MHz bandwidths. Users of these phones faced challenges such as limited range, poor sound quality but most of all they faced problems with interference. Devices such as fridges, TVs and computers emitted low-based interference that diminished the clarity and range of cordless phone conversations. By the early 1990's, as people purchased more cordless phones, baby monitors and pagers the traffic was increased and the FCC opened up the 900 MHz range.

Because of their improved range and clarify, the 900 MHz phones quickly became a standard household appliance. As the number of 900 MHz phones increased, so did the subsequent traffic. So next the FCC opened up another range of frequencies: the 2.4 GHz band. Though this frequency was new for phones, the 2.4 GHz band was also being used for wireless LANs and microwave ovens emit 2.4 GHz. So then the FCC opened up the 5.8 GHz band.

The new 5.8 GHz phones offer the latest in cordless telephone technology with the best clarity, range and possibly security. The biggest advantage to a 5.8 GHz phone is that its frequency band is less trafficked than the 2.4 GHz band, resulting in less interference.


The other factor to consider is the number of obstructions in your home or office . I remember learning in science about how transmitters and receivers work and how obstructions can affect the strength of a radio signal. Cordless phones use this same concept. A lower frequency will usually provide a better range because the signal's wavelength is longer and can travel around obstructions better.

So in theory a 900 MHz phone should work better than a 2.4 GHz phone. However, this isn't always so. If a cordless phone is used in your home or office, then obstacles such as equipment, walls and doors obstruct the path and prevent signals from traveling as well as they could in a less densely occupied area. The fewer obstructions there are, the easier it is for signals to be deflected and find the reception antenna.


Another factor to keep in mind is security. As technology advances so do ways to take advantage of this technology. Cordless telephones are really just small radio transmitters and receivers, so if you use a cordless phone with poor security, then anyone with a scanner can tune in and hear your entire conversation. However, most inexpensive radio scanners can only access frequencies of 512 MHz or the 900 MHz frequency.

On the other hand, even the pricier scanners can't cover the 2.4 GHz frequencies used by the newest, most advanced cordless phones. So if security is a concern, then you definitely want to get a cordless phone with at least a 2.4 GHz frequency.

DECT Technology

And now there is even another new phone technology to consider. DECT is a digital wireless technology that is now being adopted increasingly worldwide. DECT is used in cordless telephones, wireless offices and even wireless telephone lines to the home. This technology originated in Europe and it is a radio-access technology, rather than a comprehensive system architecture used by most cordless phones.

The Bottom Line

As you can see, there are many things to consider before purchasing a new cordless phone. One suggestion is to decide what factors are most important to you. If you just want a basic cordless phone that's inexpensive, then the lower frequency phones should work fine. However if your needs include better security, clearer phone calls or increased phone range then you will want to consider purchasing higher frequency phones.


© 2006 3CWare™.
No portion of this article may be copied or distributed without the express permission of 3CWare™