I didn't see a response from my last post, but wanted to send the following before I sign off for the night.
If disconnecting everything from the phone lines did NOT clear the issue and allow your TEST CALL to at least ring (in the calling phone), then we KNOW that the issue is with the Comcast service.
The next step that you should be able to do is to RESET your "gateway" - assuming you have such a device. The gateway is typically a LARGE box, with a bunch of lights on the front, and several cables & cords in the back, including a phone cord.
To RESET this gateway, all you need to do is remove any power connection (including any "battery pack") from the gateway and leave it disconnected for AT LEAST 2 FULL MINUTES, then reconnect the power.
What this does is "reboot & reload" any control software into that gateway, and restarts ALL of the services (TV, Internet, phone, etc.).
After that reset, reconnect the Main Base Unit of your Panasonic system and TEST for a normal dial tone AND that you can now make and receive calls (do another TEST CALL if needed).
If all that still does not restore the phone line, it would be time to give your provider a call (using an alternate line). I have their contact numbers below - if you need them - and there should be someone there 24 hours a day to answer your call. NOTE: You will be trying to reach "Technical Support".
Please let me know what you find or if you have any more questions or symptoms to report.
And when you are ready, please take a moment to rate my service level (Excellent is my goal) so that I get credit for helping you today. You should see some "smiley faces" or "stars" to do that, but please let me know if you do NOT see them or can not use them.
Thanks, ***** *****