On the phone you are moving your extension to, hit the voice mail button.
As it's asking for a password, hit #
Enter your extension when prompted.
Enter your voice mail password when prompted.
Choose option 7 - "To change mailbox options"
Choose option 3 - "To reassign your extension"
Choose option 1 - "To assign your extension to this telephone"
The system will hang up, and your extension will be assigned.
To unassign your extension:
Hit the voice mail button on the phone.
Enter your password when prompted.
Choose option 7 - "To change mailbox options"
Choose Option 3 - "To reassign your extension"
Choose option 2 - "To unassign your extension"