Google Voice needs to be linked to a valid +1 land or mobile number to function long term. My google voice number lasted for almost exactly 6 months after the us cell number it was linked to was disconnected (moved overseas for a while). It’s classification as a valid mobile lasted a bit less long and now I can not use it to send/receive SMS at all (voice mail works but it will not ring through and I can no longer use it to call. Before that many banks etc stopped Sending SMS 2fa messages through (as the are supposed according to latest NIST guidelines). Thankfully (?) the same banks seem ok to do voice 2fa to my overseas number. Sadly the still do not support better mfa Authenticators.

Would love to know how to maintain a US SMS presence without sketchy obviously for spammers products.