I don't personally use Phreeli, but I got really excited when it was first announced, so I was trying to learn more about it. I came across this youtube video that lays out some privacy issues with the service.
- Your phone's IMEI will still be static, so T-Mobile will have access to that and can associate it with cell location data, etc. and can be associated with older data if it's a phone you've used on T-Mobile networks before (like Google Fi).
- Your SIM card's IMSI will also be static, which means very similar things as above, though it's obviously a different SIM than you were using with Fi. Still ties IMEI and IMSI together, broadening what T-Mobile can collect.
- If you keep the same phone number, then that's another easy way to link you back to other data.
He goes into some additional details, but those are some of the major takeaways I had from the video. It seems like Phreeli is really just lowering the barrier to entry for getting a phone number, which is great if that's what you're after, but it's not really a privacy thing as far as I can tell.
I'd love to hear more people's thoughts on it though.
