The WIS variation can only relate to the ordering of the microphones power. The microphone ground and shield are fixed in all cars with this module. Only the actuation of the microphones can be variable.
I recently installed VCS in a early edition W169 and used the W203 wiring diagram with total success. This simply indicates the module is the same in all cars.
The UHI module auto detects the presence of the VCS Module so long as the optical connection goes to the VCS first and then to the phone second.
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