You may always use the same phone in the same location. However, the telephone system provides a number of features that allow you to use any phone on the system to make and receive calls.

Log In
You can log in at any phone that you want to use. All your calls are then redirected to that phone and your user settings are applied to calls made and received. If it is a phone that stores your contacts and call history on the system, your contacts and call log are displayed by the phone.
Any other existing user of that phone is logged out while you are logged in.
If you were logged in on another phone, you are logged out from it.
If your phone system is in a Small Community Network (SCN) of phone systems, it may be possible to log in at extensions located on other phone systems in the network. Your system administrator will advise if you can 'remote hot desk' and what features will still be available to you when you do.
Log Out
When you log out from a phone, or are logged out by another user logging in, the telephone system may apply several actions:
If you have a normal default extension and no one else is logged in there, you return to being logged in on that phone.
If you remain logged out, you are treated the same as being on 'do not disturb' except that all calls to you go to voicemail if available.
If you have a mobile twinned number, the system administrator can configure the system so that calls are still presented to your mobile twin while you are logged out.
Your system administrator can configure a timeout which automatically logs you out if you do not use the phone in that time to make or answer a call.
Lock/Unlock
Separately from logging in and out, you can lock your phone settings. While locked, the phone can still be used to answer your calls and can be used to make internal and emergency calls. However it cannot be used to make external calls and your user settings cannot be accessed through the phones menus.
You can set your phone to automatically lock itself after a period of inactivity.

Default Short Codes

Short codes are numbers that you can dial to enable and disable various features. The following are default short codes that may be available. However, your system administrator can remove and change the short codes available to you or all users.

Log In: *35*N*P#
Log in to a phone using your extension number (N) and login code (P).
Log Out: *36
Log yourself out from the phone where you are currently logged in.