In order to hard reset a Telit t550, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
Telit t550 device will be brought back to the default configuration of a brand new device.
1. Power up the phone.
2. Enter one of these codes into the phone: *#94267357# *#3646633# *#19912006# *#118811# *#77218114# *#881188#. Confirm.
3. Wait for your phone to reset and restart. Voila, done!