In order to hard reset a BenQ-Siemens C81, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
BenQ-Siemens C81 device will be brought back to the default configuration of a brand new device.
1. First of all, turn on the phone.
2. Now open Dialer and type in this code - *#9999#
3. The device will now reboot. Hard reset operation is therefore complete.