A wireless headset includes a first earpiece and a second earpiece, where the first and second earpieces communicate with each other over a wireless link. The SIM stores the most recently used service provider in its location information. The other input terminals of the comparators 62, 64 are connected to the connecting line between an external terminal P4, to which an external resistor 12 is connected, and an FET 30. For those components that are known, no discovery is necessary and actual values of changeable parameters in the audio-related device may be obtained. The production of amidated peptides using the expression systems is also disclosed.