How it is possible to configure the Sharepoint 2010 People Picker? I want ot remove the column [Mobile Number] and add a column with the normal Phone Number.
Thanks in advance!
It depends on authentication mode you are using.
AFAIK for classic-mode authentication there is no option to set columns displayed on people picker list view (disclaimer: I never had need to dig in deep in this issue since most of my projects uses claim based auth - so maybe there is way but it is nothing obvious and simple)
For Claims-based authentication you can write your own custom claim provider.
An you can find all info needed to write own custom claims provider on blog post series by Steve Peschka. Part 3 is 'people picker related':