On snom phones "Hot Desking" allows sharing one and the same hardphone by many users.
* logging off existing user accounts and logging on new user accounts
following processes must by taken, first need to remove all identity values
- Unregistration all active SIP accounts
- Deletion of SIP identity related parameters
- Login Wizard: -> Account? -> Registrar?
Setup -> Identity X -> Login Tab -> Login Information -> Remove all identities

using the Web-UI: Identity X -> Login: "Remove All Identities"
using the Phone: Setup -> Function Keys -> Number: F_LOGOFF_ALL

By pressing the pre-programmed "snom" function key, the following screen is shown:

Registration of new account, Optional: Authentication -> Password Prompt

Press a key and enter the new extension to log on, e.g. 484

Confirm with OK and enter the registrar of the new extension to log on
Hint!
if configure an Intranet DNS for example the pbx naming sip.localdomain, so it's keep easy and didn't need to enter an registrar, this will appended from DHCP and being allready in the field