A note for users of SGS2 smartphones (Samsung firmware with Android v4.0.4):
The adapter block the SIM-menu (found as app "SMS-Services" or "Dual SIM" in the applications) of the two inserted cards and instead provides its own menu available (so-called. "STK mode").
In STK mode I could not read or change the diversions of the two cards: The SGS2 tells when the corresponding menu from the settings that no SIM card is inserted and restarts.
The SIM-menu allows selection of the point by "Dual Mode" turn the STK mode.
Then, the respective SIM-menu of the provider are visible and call forwarding can be queried as usual and change.