Cordless phones—you want one that sounds clear, works anywhere in the house and doesn't let anyone else listen to your calls. These qualities are determined by the phone's format (digital or analog) and frequency.
Phone formats
• Analog: While they are a less expensive option, analog phones can have additional noise on the line, and your conversation can be picked up by radios and other devices pretty easily.
• Digital: Just as a CD offers better sound than a cassette, a digital phone offers better sound than an analog phone. You'll enjoy clearer reception and enhanced security, as the digital format makes it much more difficult for anyone to listen in on your conversation.
• DSS: Digital Spread Spectrum technology is a special type of digital phone that offers the most secure calling. It breaks your conversation into little pieces of digital data to travel over the airwaves, so no one can eavesdrop.
Frequencies
• 2.4GHz: Although you may see 900MHz phones out there, 2.4GHz has become the standard for cordless. This frequency offers great range and substantial security from eavesdropping.
• 5.8GHz: This frequency is less crowded than 2.4GHz, so calls have less interference and are clearer. Range and security are comparable to 2.4GHz. Wireless home networks work on 2.4GHz frequency, so if you're into WiFi look for a 5.8GHz phone to prevent interference.
Digital technology
Perhaps the biggest advances in sound quality, range and security have been in the realm of the new digital cordless phones. Spread spectrum provides noise-free and error-free transmission for the clearest cordless sound. It also provides call security by guarding your conversations from being monitored by another cordless phone user or even a radio scanner.
When cordless phones first hit the market reception wasn't perfect, call security was questionable and range was limited. These phones worked over the same bandwidth that baby monitors and walkie-talkies use. This is why calls placed on these phones often suffered from poor reception and interference.
Cordless phone makers began to counter this problem with phones that operate on efficient, frequencies like 900MHz and 2.4GHz.
The newest, 5.8GHz, is short on call traffic and long on power and speed. Because calls made with 5.8GHz have less traffic to contend with, call clarity and security continue to improve.
Sound quality
All cordless phones use FM frequencies, but there is a difference in sound quality between models. In addition to the new digital technology, having switchable channels can greatly influence your phone's sound quality.
Appliances and other electronic devices can produce radio interference, so many phones can transmit on more than one channel. Better cordless phones have as many as 100 channels. If there is interference on one channel you can switch to another channel to reduce interference. Many new phones switch channels automatically.
Range
Most cordless handsets can be carried anywhere around the house or yard. The maximum rated distance is 1,000' for older cordless phones and up to 7,000' for 900MHz. Some 2.4GHZ, and 5.8GHz phones may be able to reach even further away.
Various environmental factors can reduce the effective range of your cordless phone. Electrical appliances produce radio interference that can reduce the range of the phone. If you are trying to use your phone outside of your home, variations in terrain can also affect the signal from your handset to your receiver. Aluminum siding and wire mesh in walls and floors can also reduce, or block, the range.
Security
The phone industry has come up with several technologies to prevent eavesdropping on cordless phones:
Scrambling
Transmissions are scrambled between the handset and the base, making the conversation unintelligible to people listening in.
Digital transmission
This turns the analog (sound) transmission into a digital signal. When the transmission gets to the base, it is turned back into an analog signal. If anyone listens in on the signal, they hear what sounds like a fax machine.
Digital Spread Spectrum
Digital Spread Spectrum provides the most security. Not only is the transmission digital, but the signal is divided between different frequencies. Since most radio scanners only use narrow frequency bands, they never receive the entire content of the phone's digital transmission.
Telephone answering / Caller ID
A cordless phone with an answering machine built-in reduces clutter around your phone and gives you access to cool features like:
Digital answering
Nearly all cordless phone/answering machine combinations use digital recording technology. Instead of cassette tape, incoming and outgoing messages are stored on a chip inside the phone. Recording times vary from about 14 minutes up to 30 minutes, so choose carefully based on your anticipated use.
Voice prompts
Rather than having to remember a series of commands, your cordless handset will actually talk you through the operation of your answering device for message retrieval, rewinding, etc.
Remote message retrieval
This feature allows you to play back messages through either using the touchpad on your handset or a remote phone.
Caller ID
Many of our cordless phones come with built-in Caller ID displays to make it easier to see who is calling before you pick up the receiver. Caller ID is a service offered through your local phone company.
Batteries
Because they are completely unattached to any type of socket, cordless phones rely on rechargeable batteries to operate. In addition to purchasing an extra battery for your phone, you may want to consider the following:
Battery Life
Regular NiCad batteries only last about seven days before they need recharging. NiCads are also subject to battery memory problems if not used and recharged correctly. Consider phones with newer NiMH batteries, which give you longer battery life.
Dual Battery Charger
Units that come with extra batteries and a charger separate from the handset allow you to charge one battery while you use the other in your phone.
Speakerphone / intercom
Many cordless phones have a speakerphone built-into the base, giving you two phones in one. A few of these models also allow you to use the base and phone as an intercom system. A person can use the base to talk to whoever has the handset and vice-versa.
Other features
Dual Line Capability
If you run a small business or simply have more than one phone line out of your house, you may want a phone that can handle dual lines. That way the same phone can be used to make or receive calls on either line. In some cases, you can transfer calls between lines and even make conference calls between multiple lines of your phone. Like many phone services, you must arrange with your phone company to have more than one telephone line/number.
Paging/Handset Locator
Because you can take a cordless phone's handset anywhere, you can also end up leaving it anywhere, including under the sofa cushions or in the basement. Paging allows you to ring the handset from the base station, making it easier to find a misplaced phone.
Keypad on Base
This feature is simply another keypad on the base station of the phone. This is useful when your handset is charging on the base.
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Click & Learn: Cordless phones
