Should have known. Support from GV claims it’s not their fault. Entire response from them quoted below:
Thank you for contacting Google Voice Support.
We understand you are having issues receiving short codes from Smartthings service. We are committed to guiding you accordingly.
We’d like to bring to your attention some important information regarding the use of Google Voice for certain services, particularly those involving security codes or short codes. It has come to our notice that many services and shortcodes may no longer work with Google Voice for security reasons.
Various entities, including banks and other business organizations, are taking steps to enhance security measures by limiting the use of phone numbers to true mobile carrier numbers. Sadly, Google Voice numbers, while versatile and convenient, do not fall into the category of true mobile carrier numbers.
To elaborate further, Google Voice numbers are SMS-enabled, fixed-VoIP numbers, and the SMS functionality is facilitated through third-party SMS gateway services. This structure may pose compatibility issues with services that prioritize true mobile numbers for security or verification purposes.
I’m afraid these security policies are beyond the control of Google, and certain companies, especially banks and other businesses, have started enforcing restrictions on the types of phone numbers accepted for receiving security codes. As Google Voice numbers do not qualify as true mobile numbers, they may not be accepted by such services.
We can assure you that no changes were made to your account or settings related to receiving short codes. Everything is functioning normally on our end, and there are no issues or hindrances.