I was pretty stoked to set up SMS authentication for access control for our guest SSID. When I, and several others, tested it, it worked perfectly. However, I have come across several guests who are not able to authenticate. When the submit their phone number, they receive an "invalid mobile number" (or something similar). I have verified that in each case they are regular US-based area codes and numbers.
Has anyone else come across this issue and found a solution?
I have posted this on Twilio also with no solutions.