Resetting Mitel phones using the phone interface

1. Press the Options, or Settings key on the phone.
2. Press the  Advanced key on the phone.
3. Enter the phone admin's password. The default password is. 22222. (or 73738)
4. Press. Enter. .
5. Go to. Reset > Factory default. , then select. Yes. in response to the prompt.

Factory resetting Mitel 6920 IP phone - YouTube