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The speaker itself does not limit the acoustic level or is protected against overload. This protection circuit is implemented in the telephone. If you use the handset for other projects, you have to implement this protection circuit also.

This information is provided, if you like to use the handset for other projects (contact our sales).\ If like to use the handset interface for other hardware, like special headsets, please take a look at the headset interface also.


Jack Pinout of Handset Jack in the Receiver
Pin Connected to
1 Microphone +
2 Speaker +
3 Speaker -
4 Microphone -


Item Value Unit
Sensitivity -45 dB (0 dB = 1V/Pa)
Impedance 2.2 kOhm
Operation voltage 2 V
Current consumption (max.) 0,5 mA


Item Value Unit
Sensitivity 91 dB (1 mW / 1 cm)
Impedance 100 Ohm
Power Rating 0.03 W (permanent)
Frequency Range 70 - 10000 Hz


The speaker is a standard electrodynamic speaker. It is expected to work with hearing aids with electrodynamic coupling (Telecoil), but has not yet been tested for this purpose.