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Cordless phones

More and more people also use cordless phones in their homes. There are three different technologies (CT1+, CT2, DECT), whereby the portion of DECT cordless phones continues to increase.

CT1+ The information is transmitted in an analog manner, not pulsed, with a power output of 10 mW. This phone technology, which has been predominant in the past, only emits wireless radiation during a phone call. (uplink frequency—from handset to base station—885 to 887 Hz, downlink frequency—from base station to handset—930 to 932 MHz)

CT2 This is a digital technology that transmits information with periodic pulses (500 Hz) and a power output of 10 mW. These cordless phones also only emit wireless radiation during a phone call (frequency: 864 to 868 MHz). These phones were sold for only a short period of time and are not available anymore.

DECTThe information is transmitted digitally with periodic pulses (100 Hz) and a power output of 250 mW (milliwatts). The base station constantly transmits signals, regardless if somebody makes a phone call or not (frequency: 1880 to 1900 MHz in Europe and 1920 to 1930 MHz in North America). This technology makes it possible to use up to eight additional handsets per base station.
In over 90% of all cases, however, only one handset is used per base station and we could do without the pulsed signal.
For further information on CT1+, DECT, and DECT with ECO mode go to
This information is available in German only.

Should you still own a cordless phone based on CT1+ (analog and unpulsed) or CT2 (pulsed), which only emit wireless radiation during phone calls, excessive exposures can be avoided by reducing the number and length of phone calls.

Since mid-2008 DECT cordless phones are available with ECO mode and ECO mode PLUS. ECO mode PLUS models, whose ECO mode is only active after this function has been activated at the display of the mobile handset, can be recommended because this function deactivates the continuous transmission of the beacon signal. Unfortunately this complete deactivation does not occur in all devices. Some ECO mode models by Siemens still emit short signals in irregular intervals.

Even though the wireless emission of a DECT base station can penetrate several walls, there will be higher and lower exposed areas in the house. In any case, such a base station should not be placed in the bedroom. To be on the safe side, you can always go back to a "good old-fashioned wired phone."

In 1999 a resolution was presented to the then federal Environment Minister Trittin that requested to ban DECT technology. The resolution has been supported by the Interdisciplinary Society of Environmental Medicine in Bad Säckingen (IGUMED), the Institute of Environmental Health in Bad Emstal, German branch of the International Society of Doctors for the Environment (ISDE) in Bremen, Society for Environmental and Human Toxicology in Würzburg (DGUHT), various scientists (e.g. Dr. Lebrecht von Klitzing, Dr. Ulrich Warnke), the German Association of Building Biology Professionals (VB) in Lauf, and other initiatives.

The following companies offer products protecting against RF or wireless radiation:

Floors Biologa    
Walls Biologa Rigips klimaPOR
  STO BioSol KS
Windows NEHER BioSol Biologa
Doors NEHER BioSol Biologa
Ceilings Rigips BioSol Biologa
Roofs Bauder Ziegelmeier  
Rooms Biologa Rigips STO
  BioSol KS  

All products at a glance...


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