You’re on the right track.
Some points here to add to this - note my threat model might be more strict.
- Its good to not give out any base number that is linked to a physical sim card. Physical sim cards can be used to track you with cell site locations, and are vulnerable to sim swap attacks.
- Lets start with a base phone. This phone is a prepaid sim card, bought cash, registered under an alias. Don’t give this number out to anyone, nor use it anywhere. Only you know this number. This will prevent anyone from being able to find your location using the phone, or attack this number with sim swap attacks. Some people go further, and avoid grid referencing this phone by only using it at locations away from their home.
- On an app like jmp chat or mysudo you can have many different numbers. You can use a separate number for communications apps, calling friends or family, and 2FA codes.
- If some sites don’t allow VOIP, then I would purchase separate sim cards cash, burner phones, use these phones to register accounts on the main phone. These phones would typically be stored in a Faraday bag when not in use, and only used outside of my home for the purpose of registering an account with the burner number.
- To avoid the base phone from being grid referenced to your location, I use a seperate device without cellular service (ie laptop with signal, or ipad with no sim card) whenever I am at my home. This is so there are 0 cell phone signals associated with my address, nor are there any phone numbers actually registered to my name.
- If I want a burner phone or other line for a specific narrow purpose (lets say going on a trip), I can buy a new temp device cash, use it for this purpose, then dispose of it.
- I never use multiple cellphones at the same time, the other ones are always stored in faraday bags to prevent correlation between cellphones. Lets say everyday on your drive to work, there are two cell phones in your vehicle, these cell phones will be easily linked with you since they typically travel together - same reason I don’t use them at my house.
- For stores rewards programs or whatever, these people don’t even need a real number. I literally just open a site like https://smstome.com/ on my phone, find a random number and use that. Or I give them their own store’s phone number, they never verify anything.