Landline model DL72210

Unplug your phone from the service and see if those calls still go to the same message to see if it's from your phone or your provider. 

I did unplug both from electricity and phone service and I also unplugged the batteries in the phone for over an hour and it still does it.

Then it's being blocked by your providers services not your phone. Check your providers blocking service. 

Hello @TheFlint,

We understand how important it is to stay connected. Let's guide you in the right direction.

We recommend that you co-ordinate with our POTS(Plain Old Telephone Service) team at 877-353-5972 for further assistance.

Hope this helps!

ChrisM, AT&T Community Forums Specialist

Called above number and they did not help

I did change phones to see if a different phone would let call come through and it didn't so now we know it is provider which is Frontier and they are terrible to try to talk to and do not want to help.  So unsure what to do at this point.  Maybe get rid of Frontier and switch to different provider.

You might want to check their blocking features to make sure you didn't accidentally block something. Just FYI you proved it when you unplugged your phone from the line and the problem still existed. 

Called above number and they did not help

Of course they couldn't.  You're not an AT&T telephone service customer.  That number can only help AT&T telephone service customers.  You could call the corresponding Frontier number, perhaps.

As spoom2 says, you can check with Frontier to look at the call blocking features Frontier may have that might have gotten inadvertently enabled.

https://frontier.com/helpcenter/phone/calling-features lists the various services you may have and has links on how to operate them.  Look hard at "Call Block" or perhaps "Anonymous Call Block" if the caller is perhaps blocking their Caller ID from being sent.