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Do you have caller ID working on any phones on the panasonic system now and do you have caller ID from the phone company. How many total phones (corded and cordless) are connected to the 616?
You need caller ID cards in the Panasonic which probably were not installed since you didn't have phones with caller ID.
Here is the card:
They are a little cheaper on ebay.
You need one card for every 3 CO input lines from the phone company.
Here is the manual