[maemo-users] Cannot turn off call forwarding

[From: Tanuva]

Moin,

I'm desperately trying to turn off call forwarding for my sim card, but
every time I reopen the "phone" (translated literally...) settings,
forwarding to my provider's mobile box is turned on again. What might
cause that? Can the sim (say: provider) force me to enable forwarding or
is there a bug?
The sim is a german rather recent Alice/HanseNet one.

Marcel