What does my SIM actually carry?

Every SIM card is tied to an IMSI (International Mobile Subscriber Identity) — a unique number that identifies you to the network. Pair that with your MSISDN (your actual phone number), your name, DOB and address at sign-up, and your carrier is sitting on a tidy, structured profile of who you are and how to reach you.

Why new numbers attract spam so fast?

There isn’t one single cause — a few realistic explanations exist, and they’re not mutually exclusive:

→ 𝗥𝗲𝗰𝘆𝗰𝗹𝗲𝗱 𝗻𝘂𝗺𝗯𝗲𝗿𝘀. Telcos reissue disconnected numbers after a cooling-off period. If the previous owner was already on scam-dialer lists, you inherit the calls.

→ 𝗗𝗮𝘁𝗮 𝗯𝗿𝗲𝗮𝗰𝗵𝗲𝘀. Optus’s 2022 breach exposed the personal details of around 10 million Australians. Once that data is out, it circulates on scam lists for years — long after most people have forgotten it happened.

→ 𝗥𝗲𝘁𝗮𝗶𝗹𝗲𝗿/𝗱𝗲𝗮𝗹𝗲𝗿 𝗹𝗲𝗮𝗸𝗮𝗴𝗲. Third-party kiosks and resellers handle your ID at point of sale. Not all of them treat that data with the same care as the carrier itself.

→ 𝗪𝗲𝗮𝗸 𝗽𝗼𝗿𝘁𝗶𝗻𝗴/𝗦𝗜𝗠-𝘀𝘄𝗮𝗽 𝗰𝗼𝗻𝘁𝗿𝗼𝗹𝘀. ACMA’s own 2022 determination exists precisely because identity checks for SIM-swaps and account changes were too weak — a gap scammers were actively exploiting.

We are not claiming:

Australian carriers are “actively selling” customer data to spam networks. We haven’t seen credible evidence of that specifically — and it’s a serious allegation to level at named companies. What’s well documented is sloppy security, breach history, and incentives that don’t always favour the customer. That’s a different (and still serious) problem.

What can you do?

✅ Ask your carrier to add a port-out/SIM-swap PIN or passphrase
✅ Check if your new number is “recycled” — ask the retailer directly
✅ Register with the Do Not Call Register (it won’t stop overseas scammers, but it filters legitimate telemarketers)
✅ Report persistent scam numbers to Scamwatch and your telco — this is how the industry’s 2.2B+ blocked scam calls tally grows
✅ Treat SMS one-time codes as a security control, not an inconvenience

Our phone number has become a de facto identity key — for banking 2FA, MyGov, socials — while the industry protecting it is still catching up on basic identity verification.

What about a private cell service?

Enter Cape.co – as it states, it is totally private, in fact it rotates your IMSI number daily so not even the system knows who you are. Pretty sweet right, well we see this service is only available in the states at the moment, perhaps in time this will be available to Australia.