Reassign Extension to any Phone Jay Coppin August 21, 2017 16:14 Updated Follow Press # #. Enter the extension number you wish to reassign. Enter the password for that extension. Press Option 7, Mailbox Options. Press Option 3, Reassign Your Extension. Press Option 1, Assign Your Extension To This Telephone. Related articles Attaching a Mailbox Comments 0 comments Please sign in to leave a comment.