Sounds like you want a Google Voice Number or similar service, but now you're spending money for someone else's awful software, and in some cases, some places will flag your number if its google voice and outright refuse to let you in.
If you load it with 10 dollars in minutes, it'll be good forever. But I'm not sure what TracFone has for an inactive policy
It works surprisingly well. I can easily turn off the second line in Settings without removing it.
I could’ve bought an unlocked phone with cash somewhere and used the SIM in that. They wouldn’t know who I was.
I didn’t do that because it was inconvenient and it wouldn’t be anonymous once I started using it for SMS authentication.