Yealink T48S Skype For Business Edition User Manual page 79

You will be automatically signed out of the phone after five unsuccessful unlock attempts.
Changing Your lock PIN
To change the phone lock PIN via phone user interface:
Tap Menu->Setting->Basic->Phone Lock.
1.
Select Enabled from the pull-down list of Phone Lock.
2.
Enter the lock PIN in the Current PIN field.
3.
Enter the lock PIN in the New PIN field.
4.
Enter the lock PIN again in the Confirm PIN field.
5.
Tap to change the lock PIN.
6.
Lock PIN is configurable via web user interface at the path Settings->Phone Lock.
Resetting Your lock PIN
If you forget your lock PIN, you can reset the lock PIN from your phone using your login
password.
Customizing Your Phone
77