xfinity voice support

I have used Xfinity voice for a long time. I recently upgraded my voice modem. The  (Panasonic) phones appear to be connected but the all say the line is busy. I have restarted the modem. I have checked all the phones. I have plugged a different phone into the modem with the same result. I have tried talking with a dozen AI chatboxes and looked at many FAQs but nothing has helped.

The modem is working for internet and  many connected devices. Is there anything else I can do?