SIM vs eSIM vs VoIP uses?

Snowy

I have had a gentle start to GOS recently after installing and using it on a Pixel Tablet, and I think I'm ready to try it with a phone now (new Pixel 8 on its way).

I'm interested in user's experiences and views on voice and messaging setup.

Accepting that I will use encrypted FOSS messaging apps as far as possible, there will still be a real world need to be reachable using cellular telephony and SMS. I'd also like to be able to use my (very) old cell number as a background service somehow, if that's practical.

I know that I can port my old cell number to a VoIP service which should break cell based tracking. But I understand that SMS over VoIP wont allow me to reliably receive OTP messages.

I have thought about using the eSIM for my old cell number, but I suspect that would be a bad ideal.

I've also thought about setting up an older 3G dumb phone to auto-forward calls from my old number, but I don't think that dumb phones will forward SMS..

What services have other GOS users allocated to either SIM, eSIM, or VoIP to optimize for accessibility vs privacy and security?

My initial use case is for a low threat daily driver phone. But once I've got this working I will be moving on to set up a second Pixel 8 for my activist work, which will have a higher risk of exposure to IMSI scanning and possible active intrusion. I won't be using my old cell umber on that phone, of course.

I'm UK based by the way, and don't foresee a need for international roaming.

Interested in your thoughts.

JollyRancher

How much money are you willing to spend and do you have friends/allies you can trust in the US?

You are in the UK so step 1 of actually having any security or privacy is to appear to be outside of the UK.

If you have someone you trust in the US, or can afford to higher an attorney to provide the service, have them buy a cheapo phone and slap a Mint Mobile Sim into it (the cheap option, Cape is the better but substantially more expensive option). Use this number for anything that needs a number to sign up.

You want another Sim that you use solely for Signal as a court order will get the number associated with a Signal username and you don't want that number linked to anything else.

Realistically, you also want to set up a New Mexico LLC with its own bank account (use a local US bank with no international footprint). New Mexico let's you keep your identity off of any public facing documents. FinCen will know who you are but they aren't inclined to tell the UK short of serious criminal charges. This bank account can pay for the things you need paid for outside of the UK.

Use the US company to pay for a server and set up your own VPN to route into Mullvad.

All communications should be via secure, end to end encrypted, messenger app routed through the VPN. Anything that routes through UK ISP's/telecoms should be assumed compromised and being viewable on demand by the UK government.

Bluntly, you aren't going to seriously hamper UK law enforcement as a UK citizen inside the UK using UK telecom infrastructure. IMEI based location tracking is alive and well and will let the authorities track your phone with sub meter level accuracy whenever airplane mode is off.

Anything you register for with a UK phone number or pay for with a UK bank account is enough of a hook to get UK court orders obeyed by most corporate entities. So you don't want to be doing that.