# Foreign SIMs — the number you buy abroad can still carry your name > A SIM bought in another country feels anonymous: cash at a kiosk, a local number, none of your home accounts. But most countries now register SIMs to a passport, every SIM reports the phone it sits in, and the carrier logs where that pair travels. The number is new; the link to you may not be. The goal abroad is not a magic anonymous SIM — it is keeping the SIM, the phone and your identity from being tied together in one record. Markdown twin of https://xmr.club/opsec/22-foreign-sim-strategies. CC-BY-4.0. Attribute "xmr.club". ## At a glance - Canonical: https://xmr.club/opsec/22-foreign-sim-strategies - Series: #OPSEC52 — weekly threat-model-first OPSEC cards - Week: 22 - Pillar: Travel & border - Difficulty: intermediate - Cost: $0–$30/trip - Language: en - Published: 2026-10-19 ## Body # OPSEC52 / Week 22 — Foreign SIMs: the number you buy abroad can still carry your name > A SIM bought in another country feels anonymous — cash, a local number, none of your home accounts. But most countries register SIMs to a passport, every SIM reports the phone it sits in, and the carrier logs where that pair travels. The number is new; the link to you may not be. **Threat model:** the selling carrier and the state it answers to — SIM-registration laws that bind the number to your passport, IMEI logging that ties a SIM to a specific handset (and every other SIM it has carried), location logs kept for months, and roaming agreements that copy your movements back to your home carrier. ## What actually links a "foreign SIM" to you Three links survive the border, and most travelers only think about the first. **Registration at point of sale.** A large and growing share of countries require ID to activate a SIM — a passport scan at the airport kiosk, a photo at the phone shop. That single step binds the number to your legal identity before you ever send a message. "Local SIM" and "anonymous SIM" are not the same thing, and in most of Europe, much of Asia and the Gulf they are opposites. **The handset.** Your phone broadcasts its IMEI to every network it joins. Put a new foreign SIM into the phone that carried your home SIM, and the carrier — and anyone with its logs — can tie the two numbers together through the shared hardware. A fresh number in a known phone is a renamed line, not a new identity. **The pattern.** Even an unregistered prepaid SIM deanonymizes itself through behavior: it lights up the same cell towers as your hotel, logs into the same accounts, and travels on the same route as a phone the state already knows. Metadata doesn't need your name when the movement is a fingerprint. ## What to do today - **Decide what the SIM is for first.** Maps, ride-hailing and restaurant bookings need data, not identity cover — a travel eSIM is fine. A number you intend to keep separate from your legal self is a different job and needs the steps below. - **Separate the SIM from your real phone.** For anything sensitive, use a second handset that has never carried your home SIM. One phone, one identity — don't mix a compartmentalized SIM into the device the state already maps (see Week 7, phone compartmentalization). - **Prefer a data-only travel eSIM for convenience.** A travel eSIM bought before the trip — ideally without KYC, paid in crypto (our own [eSIM desk](https://kyc.rip) exists for this) — gives you connectivity with no passport scan at a foreign counter and no local registration record in your name. Route the sensitive traffic through your own VPN or Tor on top (Week 1, Week 19). - **Know the registration law before you land.** If the country registers SIMs to ID, assume the number is bound to your passport from minute one. Plan around it — don't discover it at the kiosk. - **Keep the voice/SMS number and the data path apart.** If you need an SMS-receivable number, get it from a service built for that (a no-KYC SMS number), not from a passport-registered local SIM you then use for everything. - **Turn off your home SIM, don't just roam on it.** Roaming hands your home carrier a running log of every foreign network you touched. If you want a clean break, power the home line down — pulling it, not just toggling data. ## For crypto users Never run an exchange login, a wallet, or a node over a SIM registered to your passport in a country you're visiting — you've handed one carrier the link between your identity, your location and your on-chain activity. If you must transact while traveling, do it over a data-only eSIM (bought without ID, ideally pre-trip) plus a VPN or Tor, on a phone that isn't your daily driver, and never enter a seed phrase on a device sitting on a network you don't control. ## Common mistakes - **"I paid cash, so it's anonymous."** Cash hides the payment, not the passport scan. If activation needed your ID, the number is registered regardless of how you paid. - **One phone for the home SIM and the foreign SIM.** The shared IMEI quietly welds the two numbers together. A new SIM in an old phone buys you almost nothing. - **Leaving the home line roaming "just in case."** That's a continuous beacon to your home carrier. Decide before the trip whether the home number travels at all. - **Treating a travel eSIM as identity cover.** A data eSIM is great for not leaving a registration trail abroad — but it is not a disguise. Your accounts and your route still identify you unless you tunnel and compartmentalize. ## This week's move Before your next trip, set it once: a second phone with no home-SIM history, a data-only eSIM bought ahead of time (no KYC, paid in crypto), your VPN with a kill switch, and a decision — written down — about whether your home number powers off at the gate. Land already compartmentalized instead of improvising at a foreign counter. --- *OPSEC52 is xmr.club's weekly OPSEC series. Curated by [Cyber Satoshi](https://x.com/xbtoshi). Series index: [/opsec](https://xmr.club/opsec). A complement to — not a replacement for — Sam Bent's daily #OPSEC365. See also Week 4 (phone isolation), Week 7 (phone compartmentalization), Week 20 (border device searches) and Week 21 (hotel and public Wi-Fi).* ## Related - HTML: https://xmr.club/opsec/22-foreign-sim-strategies - Series index: https://xmr.club/opsec - Twin index: https://xmr.club/llm/opsec.txt