Given his location and handle, it's not likely that dr_frost_dk is using the same network as me, I'll agree, but not impossible. Perhaps he's visiting friends or relatives in the US for the month and stopped by a WalMart* to get a cheap prepaid SIM with international calling included on the same MVNO as me. But until we know for sure, the network operator in question only exists in a probabilistic state, like Schrödinger's cat and my Jolla tablet.

Of course, you're almost certainly correct about it being a carrier-specific problem, not some sudden global issue or code-rot problem.

So let us know, dr_frost_dk, what happens if/when you can get that info out of your carrier and how it turns out.

*This is the new-style WalMart signage, with the asterisk at the end perhaps pointing to a footnote reading: "Target is cleaner and almost as cheap".