Thanks to all of you helpful souls!
Sometimes it’s a difficult to find the right stuff.
(It took me almost 2 hours to find the right thread and software
to unlock my G4 T-Mobile Vario Wizard.)
That’s why I created this post.
Hopefully it helps people to locate the respective information
My device is a German T-Mobile (G4)
ROM: 188.8.131.52 GER (3/9/06)
I have downloaded Lokiwiz 3.0a and followed the procedure described here:
THANK YOU very much Ricardo Afonso!