Thanks for the clear and precise explanation Obi! I have a follow up question. You said you receive bank and credit card SMS through google voice. What is the usecase for TextFree? Is it just an alternative to google voice app? Can you still get SMS from your bank using TextFree?
Mainly redundancy. I keep both numbers on file with banks and whatnot, usually Google Voice as my mobile number and TextFree as my home number. Some institutions or some days one is better than the other for whatever reason.
For example, USAA allows me to receive emailed verification codes when logging into the website, but requires SMS when calling in via their phone system. Their phone system asks me to enter the last 4 digits of the phone number where I want to receive the SMS code. Textfree always works fine, but when I type the last 4 digits of my Google Voice number it takes me back to the main menu for some reason, lol.
Another example is Capital One - if you use a verification code option more than two or three times during the course of a day, it greys it out and you're forced to choose another option. There was also a week or two awhile back where I wasn't getting their codes via Google Voice for some reason, but Textfree continued to work fine.
I haven't had any issues yet between Google Voice and Textfree, but another app I've used in past for verification codes is called "Numero eSIM." With Numero you can purchase a subscription to a U.S. virtual phone number, or for a little more you can purchase a subscription to a U.S. "social media" phone number that's supposed allow you to receive SMS verification codes. Prices are in Euros and a 1-month subscription is €2.49 and a 1-year subscription is €12. I'll keep using the free options as long as they work, but if I ran into issues I would try Numero for a month and see if it still plays nice with financial institutions.
Aside from SMS, I have biometric (fingerprint) login enabled on as many apps as possible, which sometimes allows you to "skip" SMS verification altogether. Some institutions have other workarounds to bypass phone verification completely. For example, if I log into the Citi website on my computer using my username and password it usually wants to call me at my Google Voice number and make me listen to a Citi verification code. Alternatively, Citi displays a QR code on the desktop login screen, and I can open the Citi app on my phone, scan the QR code and my fingerprint in the Citi app, and it automatically logs me in on the desktop with no password or additional verification required.The Capital One website allows me the option to do push notifications to my phone instead of SMS, so I get a little pop-up on my phone asking me to confirm or deny the login attempt.
Setting up Google Authenticator (I use an app called 2FAS), can be useful. I have 20+ websites at the moment where I can generate verification codes if needed via 2FAS, including Paypal, Facebook, Amazon, Uber, and MercadoLibre.
Less widely supported and probably not necessary for the average person, but I also have two USB-C YubiKeys (one as a backup) that make life a lot easier on certain websites. For example, my YubiKeys work for anything Google related. I can log in to Google or Gmail on any computer using just my Yubikey and my 8-digit pin - nothing else is required, not even my regular Google password. The concept being that I'm in possession of something uniquely physical (the YubiKey), and something only I know (my YubiKey pin). Yubikey is supported by many U.S. government websites, and I use my Yubikey to bypass verification on the Social Security, VA, and CBP (Global Entry) websites. Any website that supports ID.me or Login.gov can be set up to use YubiKey for two-factor authentication.
I also use YubiKey in conjunction with my password manager (BitWarden). I have a different 20-25 character password for every website I use, all generated and stored in BitWarden. I honestly don't know or remember any of them as they're meant to be impossible to remember. If I need to log into Paypal or whatever else, I open Bitwarden, type my Bitwarden "master password," then insert my Yubikey and type my YubiKey pin. Only then do I have access to Bitwarden and can then copy and paste the unique Paypal password. I keep the Yubikeys in separate places, but in the off chance I were to lose both of them I have Bitwarden set up to accept Google Authenticator codes from 2FAS as well. In that scenario to access Bitwarden I would still need my Bitwarden master password, my password to unlock my phone, my fingerprint to open the 2FAS app on my phone, and then the six digit code from 2FAS to verify with Bitwarden.
Anyways, sorry, I know this a lot and I've never been known for my brevity. Hope this helps - feel free to ask me anything else here or via PM.