The present invention relates to a method for frequency calibration of a testing apparatus for testing or mobile terminals, such as mobile or cellular telephones, provided for operation in a mobile communication net. The method comprises providing a first, a second and a third steering input. Such a hand free device can be simultaneously coupled to multiple communication devices and allows the same to be operable at the same time. A first portion of the gate electrode defined over the diffusion region forms a first transistor segment having the operable transistor threshold voltage. , b0 of input data B as an active bit. The system has a patient bed system, which is detachably attached to the base, and has a contact surface for supporting the patient.