PS (the edit timeout expired) It may help a bit to keep the phone number (if any) of your KYC-ed SIM confidential. If you don't plan to use the call/SMS features of your SIM, no one needs to be given the number. The cell network etc unavoidably know it, but if you avoid giving it out to anyone else, that reduces the chances of them being able to use it against you. While it may be dated in many respects, you might like to read JJ Luna's "How to be invisible" for some insights. Your phone number can be used in social engineering attacks, for example, so keeping it confidential adds an extra hurdle the attacker has to jump over if they don't have privileged access to the KYC-ed data.

    sr967 Thank you so much for your long and detailed response. It really helps me understand more of this and I can see clearly that you're quite knowledgeable of this stuff.

    I'm thinking of opting for a KYC data only sim for mobile data and then using VoIP numbers for phone calls. But because I don't really use phone calls/sms, and instead use Signal, those VoIP numbers will barely get used anyway.

    This is a question I have, even after reading Michael Bazzell's privacy guides.

    Would it be better to just get a mobile data KYC SIM that has no phone number attached, or to just get a normal KYC SIM that has a phone number on there but never use that or share that phone number with anyone?
    Thank you so much.

        DeletedUser84 Thanks for your kind words!

        I think all SIMs have a phone number anyway, even if it doesn't actually work in the traditional sense. The silent.link data only SIMs do - it is mentioned in their FAQ - and I've seen 5G data only SIMs used in 5G home routers with numbers too. There's also this admittedly rather old stackexchange post saying the same.

        It probably makes little difference in practice if you don't plan to give the number out anyway.

        If you can get a better price on a SIM with calls+text+data and just not use the calls+text compared to specifically buying a data-only SIM, that is probably just as good from a privacy point of view and obviously a win financially. Depending on your precise threat model, having a SIM capable of calls+text as well just might come in handy in some kind of emergency (I need to call X right now and mobile data isn't working), even if you plan never to use it.

        (The "practical guide for the paranoid" I linked to does say there may be a reduction in attack surface from not having calls or texts, but that it doesn't particularly matter otherwise.)

            sr967 Thanks again for your response, I really appreciate it.

            Here in Australia, at least with the carrier I'm interested in, the data only SIM is actually cheaper and offers more data compared to a regular SIM with data, calls and SMS.

            So I'll think I'll go with the data only KYC SIM, thanks again for your help and guidance. And if you have anything else to share, feel free to because I'd love to learn more.

              To the topic of credit/debit cards and how to get them anonimously:

              In some jurisdictions, it is still possible for a company to provide these cards to you WITHOUT knowing anything about who you are IF the card have a restriction, that it can not by used for cash withdraw and money transfer. (You can use it to buy something, but not to deposit money to a bank or withdraw cash.)

              Some companies decided to use that opportunity to provide no-kyc cards that you can top up with bitcoin (or other cryptocurencies) and buy something online.

              Great example of that is paywithmoon.com.

              So if the Currier (or some other merchant) do not need the card to by from Australia, it may be worth it to try.

              And if the the Australian curriers do not accepts cards from outside Australia, or if it turns out that ID is required no mether how you pay, you can use the same card to buy data-only esim for tourists.

              Thare is a lot of services that sell you data esim and do not need the ID. Some are privacy oriented and take crypto. (Like silent.link that was mentioned before.) Some are just ment for tourists. (People who travel to Australia for short Holliday's do not want to upload ID to random Currier's website just to get short therm data plan)

              Good repository of tourist orriented esim's is esimdb.com. Almost non of them need the ID. But they do not accepts crypto, so the no-kyc card is a prerequisite of paying for their service anonymously.

              Blastoidea It depends of from what you are hiding.
              If you are hiding from targeted investigation, yes, you probably file eventually.

              If you just want to ensure that mass surface have hard time knowing what you are duing all day and whare you are all the time, then that is possible unless they decided to dedicated a resources to specifically track YOU (not just collect data on population in general) .

                  DeletedUser84 I still use the given SIM numbers (I have two; one for personal one for professional; my Pixel is dual-SIM. I also maintain a personal Signal and professional Molly, per MB's approach). I haven't yet gone the route of VoIP numbers with a data-only SIM. I've found trying to get my head around how to set that up to be a bit too complex. But, if there is someone who has done it here in Oz, then I might look at that again in the new year. I'd try to port my existing numbers to VoIP, as I do not want to lose them.

                      LunaticBuzz yeah I'm planning to just use VoIP numbers, and a data-only SIM. I have found 2 great providers for this. You can port your numbers no problem.

                      The Sipnetic app also just for VoIP calls/SMS is excellent, I really like it. If you need any help with this, I am familiar with setting up everything, it's quite simple.

                        petrnovak thanks heaps for your suggestions.

                        I have tried to use pre-paid cards to pay anonymously, but carriers don't accept them more unfortunately. I think they've smart-end up.

                        Regarding Silent Link, in my original post, I talk about how I generally don't trust them and how they're a bit suspicious. So I think I'll stay away from them. But thanks for that anyways.

                        I feel like in a country where there's KYC for Sims and whatnot it's probably best not to try and get a SIM, and provide a fake name because if they scan that name and it comes out that there's no person that exists with that name, then you will probably be very closely watched and maybe even targeted or attacked, or something like that.

                        With a no KYC roaming sim, you come across as less suspicious depending on the number attached to the sim, but if you're staying there for a long while EG; a couple of years, then you come across as suspicious because what tourist is holidaying in the same area for years on end.

                        And with what Sr967 said earlier, You can be deanonymized very quickly, even without using your real name attached to the sim. And then you can come across as a lot more suspicious as well.

                        What I found during my privacy journey is that you don't want to stand out in the crowd, you want to blend in, so a lot of these different ways to get a sim can actually make you stand out more and reduce your ability to blend in with the crowd.

                        I appreciate your input!

                          JollyRancher

                          Haha... I'm not an Aussie, but have spent a lot of time there. A few years ago I watched a friend buy an activated pre-paid SIM from a youth who'd used up all the credit and was just using the phone as a music player. It cost him $200. Once he had the SIM, number and account all he had to do was pick the plan he wanted and buy some credit.

                          My SIM is one of tens of thousands of company SIMs and is not associated with me directly. Same for my credit cards.