Reset your Siemens Gigaset mobile handset to factory defaults is little complicate and you need to follow these steps exactly.
- turn off the mobile handset
- press 1,4,7 at the same time and hold them
- turn the device on (while still press 1,4,7)
- if you see "Service" in the display press 4 6 8 5 4 6 3
The device will power off itself and the reset is done.
Now you can turn the device on and it acts like a factory fresh device. All individual settings are removed.