Panasonic KX-TA624/824 multiple message-waiting lights
If your KX-TA624 is a "dash three" or later version, or you have a KX-TA824, you can have more than one message-waiting light on one phone, and several phones can show the status of one mailbox.
Flip the rear memory switch to PROGRAM (or press PROGRAM if you have a PROGRAM button).Press the button you want to use.Dial 95.Dial the extension number of the other phone.Press STORE.Flip the memory switch back to SET (or press the PROGRAM button if you have one).