Flashing "TEL1" light on modem with no phone service?

Hello all!  First post on the community!

I have xfinity internet service but no voice, TV or anything else.  I am using my own Netgear CM1150V modem (which is identified properly on my account.)

I noticed recently that the "TEL1" light on my modem is flashing.  I dont' know exactly when it started, but it did not flash in the past.  I talked to customer service (via chat) and they gave me the standard response of "line in use or phone off the hook".  But when I reminded them that I did not have phone service (and do not have a phone hooked up to the modem), then they said "Your modem is not apportioned for phone so that's why it is blinking".  That would not explain why it just started blinking recently though.

Maybe it was due to a recent push of a firmware update from xfinity?  My internet is still working fine with no apparent change in speed and I don't see any changes to my account or services.

Anyone have any ideas?  Or should I just let it go as it doesn't seem to be causing a problem.  It just bugs me that something must have changed and I'd like to know why...

Thanks in advance!