# SIM registration

> SIM registration is a legal requirement in some countries to link a SIM card or eSIM to a verified identity, usually a passport, before it can be used.

Source: https://viasimo.com/glossary/sim-registration/
Also known as: SIM card registration, KYC registration, identity registration

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SIM registration is a legal requirement in some countries to link a SIM card or eSIM to a verified identity, usually a passport, before it can be used. Governments mandate it to combat fraud, spam and criminal use of anonymous numbers.

The rules vary widely. Countries including Thailand, Turkey, India, Indonesia and China require identity checks before a local SIM goes live, which is why buying a SIM at the airport usually involves handing over your passport, being photographed and waiting while a clerk scans your documents. In some places registration takes minutes; in others it means paperwork, queues or biometric checks.

Travel eSIMs usually work differently. Because they are sold as international roaming products registered to an operator in another country, they generally do not require in-country registration at all: you install the profile before you fly and connect on arrival with no counter, no forms and no passport scan. This is one of the quietest but most practical advantages of an eSIM for destinations with strict rules, such as [Thailand](/destinations/thailand/) or [Turkey](/destinations/turkey/).

A related but separate concept is device registration. Turkey, for example, requires the IMEI of a foreign phone to be registered if it is used with a local Turkish SIM beyond a limited period; short-term visitors using a [roaming](/glossary/roaming/) eSIM are generally unaffected, but long-stayers should check the current rules. Your [IMEI](/glossary/imei/) is the hardware identity of the phone itself, not the SIM.

Concrete example: two travellers land in Bangkok. One queues at a kiosk to register a local SIM with their passport; the other installed an eSIM at home and is online before reaching baggage reclaim.

For destination specifics, see our guides to the [best eSIM for Thailand](/magazine/best-esim-for-thailand/), the [best eSIM for Turkey](/magazine/best-esim-for-turkey/) and [getting online in China](/magazine/china-travel-guide-internet-access/).