Hello & Welcome to Just Answer,
I see that the other expert has had to open your question - I may be able to help if you still need help.
May I ask:
1) How many TOTAL handsets do you have with this system?
2) What phone service provider (phone company) you have for this phone line?
3) If you have ANY other devices (phones, fax, alarm system, etc.) attached to this same phone line (not part of the Panasonic system)?
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, ***** *****