This message is detailing a solved error (thanks PM & Google tech support!) so there will be a record if anyone searches for it. No further assistance is needed.
The Problem - repeated SMS error messages being received in the middle of the night:
The message: "Sorry, your plan does not include sending texts while in the US. Incoming texts are included. To add a US Roaming Add-On, visit selfserve.publicmobile.ca"
That is the message one would expect to receive while attempting to send a SMS message on a non-provisioned phone while in the US. In our case, we were not trying to send SMS messages on the Public Mobile SIM card.
It turns out that on the Pixel 7 Pro, Google defaults to assuming that all carriers now have Visual Voicemail (a really cool feature that I hope Public Mobile adds, tbh). The act of Google reaching out in the background to the Public Mobile system, attempting to set up visual Voicemail for us, was what was triggering these SMS messages (usually 5 over a 3 minute span in the middle of the night).
To fix, go into phone setting, select 'Voicemail', select the SIM card for Public Mobile, and then de-select 'Visual Voicemail' - problem solved!
Thanks again to the team at Public Mobile for chasing this down to what was causing the error, and Google for explaining how to eliminate it.
