SMS error: "Message could not be sent"

After months of trouble-free phone and SMS service (primarily to say that I'm not a new user), this morning all of my text messages result in "Message could not be sent" errors:  

Not sure if this is related to the 10DLC "campaign registry" issue, or just "something is broken", but the fact that I can't respond personally to anyone texting me is bad for business.

I am able to receive SMS, but not send to any number.  I've sent in a Support Ticket.

Anyone else experiencing this?