Submitted a ticket, and after being told to do everything I had already done over again, they called me. I happened to again mention the pulsing dial tone (which I mentioned in my original ticket) and the tech immediately realized that somehow the "do not disturb" function had been activated. Apparently, you can do this by dialing *78. To turn off the "do not disturb" function, dial *79. So if anyone else has that same problem, that's how you fix it.