Finally got an in person phone technician out who could call his support number and get the phone company to fix things on their end where I told them the problem was 3 over the phone support techs prior (I mean, I get why they can't just believe everybody who thinks they know what they're talking about). Also, there's now one fewer piece of telecom gear in the chain so that's a win. Don't know why they set it up the way they did last time they changed the hardware.
Anyway, sorry to any customers who have been trying to call while we've been trying to convince the phone company that this was an issue that they needed to fix. I believe everything should be back to working properly again.