With the exception of the RS 275, RS headsets are not Bluetooth capable. RS headsets use Digital RF (2.4 GHz) or RF (800–900 MHz), depending on the model.
The RS 120-W does use Bluetooth LE, but only for a proprietary connection to its transmitter – it does not pair with standard Bluetooth devices.
To check which type your model uses, refer to the product page or the model's technical specifications.