I have an IP Telephone (i.e. 1603, 9640, 9630, …). How I can I log out to prevent unauthorized use of my telephone during my absence ?

If you have an IP phone, there is an option that allows you to log in and out of your telephone, while maintaining your preferences and information.
To log-in to your telephone:

Step 1: At the initial screen when it prompts you for your extension, enter your extension.

Step 2: Press on Enter or OK or the pound key #.

Step 3: Enter your password.

Step 4: Press on Enter or OK or #.

NOTE: You are logged into the phone. 

To log-out of your telephone:

Step 1: Press on the Avaya Menu.

Step 2: Select Log Out.

Step 3: Press on Log Out or OK or #.