Hello & Welcome to Just Answer,
Sorry to hear of the issue you are having with your phones.
May I ask:1) The Make & Model Number of the MAIN phone system you are working with?2) How many TOTAL handsets do you have with this system?3) Are these handsets "Add on" handsets - purchased separately from the MAIN system?
Can you tell the the TOTAL number of handsets you already had registered to the Main Base Unit?
Can you look in the battery compartment of the add on handsets and see if you can find a model number there?
That should be a CSxxxx model - where xxxx is a 4-digit number.
One more thing: Were these handsets purchased as "NEW", or perhaps "used" or "refurbished"?
I see it has been a few days and I just wanted to follow up to see if you have any more questions concerning this issue or if the issue was resolved.
I look forward to any further questions or results that you may have.
Thanks, ***** *****