Buzz
Cordless phones have advanced significantly over time, evolving into high-tech consumer electronics. As technology progressed, the radio frequencies used by cordless phones have been upgraded to minimize interference issues and prevent eavesdropping by nearby phones or radio scanner users.
Frequency Bands for Cordless Phones
- 1.7 MHz - The earliest analog cordless phones operated in this frequency range, positioned just above the AM radio band. These older models are no longer available, and they were highly prone to interference from devices like fluorescent lights and nearby car ignition systems.
- 46 MHz - 47 MHz - This range is home to many older analog cordless phones. Low-power walkie-talkies and baby monitors also share these frequencies, offering 25 available channels. Some models use audio inversion for security, though these are still vulnerable to interception by radio scanners. Unscrambled versions can easily be monitored by anyone with a similar device. The density of users in a specific area can make this band quite congested.
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902 MHz - 928 MHz - Modern cordless phones operate within the 900 MHz range, typically identifiable by their shorter, non-telescoping antennas. Only digital spread spectrum (DSS) models in this range are secure and cannot be easily detected by a radio scanner. Most other models in this band are analog, making them easy targets for interception. However, the 900 MHz band is far less crowded compared to the 46-47 MHz range. These newer phones offer 80 channels, with each manufacturer using a portion of them.
- 2.7 GHz - The latest generation of cordless phones operates within the 2.7 GHz range. This band is not easily covered by radio scanners, and both analog and digital spread spectrum models are available to ensure privacy and longer range.
If you're in the market for a new cordless phone, choose one that works in the 900 MHz or 2.7 GHz range and utilizes digital spread spectrum technology for improved privacy and extended range.
Explore these resources to deepen your understanding:
- ARRL: Telephone Interference
- Cordless Telephones: Frequency List
- How Cordless Telephones Function
- Understanding the Radio Spectrum
- The Basics of Radio Communication
- How Radio Scanners Operate
- What is Digital Spread Spectrum in Cordless Phones?
- Can My Baby Monitor Be Intercepted?
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