If you have incorrectly entered in an extension's PIN 10 times, our system will automatically lock that extension. You will hear the following message: "For your protection, phone access to this extension has been locked due to invalid PIN attempts. Please contact your account administrator to unlock this extension."

To resolve this, you must contact our Customer Care team to have them unlock the extension for you. 

To find out what your extension PIN number is, see where do I find the PIN number for my extensions.