A SIM-locked phone only works with the carrier that sold it. Check your iPhone in three taps — Settings → General → About → Carrier Lock — or test an Android by inserting a different carrier’s SIM. If your phone is locked, unlocking is free in many countries, though the exact steps and waiting periods vary by carrier and region.
What SIM Lock and SIM-Free Mean
SIM Lock (Carrier Lock)
A SIM-locked phone contains a software restriction that prevents it from connecting to any mobile network other than the one that applied the lock. The restriction is set by the carrier, not by the device hardware or any cellular standard. For example, a phone locked to Carrier A will reject SIM cards from Carrier B, C, or any travel eSIM from another provider.
Carriers historically used SIM locks to recoup the subsidy paid on devices sold below retail price on postpaid contracts. The economics have shifted in many markets — subsidised bundles are less common — but SIM locks still appear on devices sold by carriers in countries without a mandatory ban.
SIM-Free (Unlocked)
An unlocked phone accepts any SIM card compatible with its supported radio frequencies. Buying travel eSIMs, swapping to a cheaper local SIM abroad, or switching carriers without buying a new device all require an unlocked phone. The term “SIM-free” is used primarily in the UK and parts of Europe; “unlocked” is the more common term in the US and globally.
SIM Lock and eSIM
The lock applies to eSIMs as well as physical SIMs. A carrier-locked iPhone or Android phone may refuse to install or activate an eSIM profile from a different carrier. If you try to add a travel eSIM and receive an error during activation, the first thing to check is whether your phone is carrier-locked. The eSIM activation troubleshooting guide covers the most common errors and their causes.
How to Check Your Phone’s Lock Status
iPhone
Apple provides a built-in carrier lock status indicator in every iPhone. The check takes under a minute:
- Open Settings
- Tap General
- Tap About
- Scroll to find Carrier Lock
If the field reads “No SIM restrictions”, the phone is unlocked. Any other message — for example, a carrier name or “SIM locked” — indicates the phone is restricted to that carrier.
This check is available on all iPhones running modern iOS versions and is confirmed by Apple’s official support page.
Android
Android does not have a single unified carrier lock indicator across all manufacturers. There are two reliable methods:
Method 1: Insert a different carrier’s SIM card The most direct test. If calls and mobile data work normally with the new SIM, the phone is unlocked. If you see “SIM not supported,” “Invalid SIM,” or “No service” after inserting a valid SIM from a different carrier, the phone is locked.
Method 2: Network operator scan (Pixel and stock Android) Go to Settings → Network & Internet → Mobile Network → Network Operators, then tap “Search networks.” If multiple carriers appear in the results, the phone is likely unlocked — but the physical SIM test described above remains the most reliable confirmation.
Samsung Galaxy Go to Settings → Connections → SIM card manager. Some Samsung models show a lock indicator there. The safest test remains inserting a different carrier’s SIM.
Finding your IMEI
Dial *#06# from the phone app, or check Settings → About Phone → IMEI. The IMEI is required when requesting an unlock from a carrier.
How SIM Lock Policy Varies by Region
United States — No Unified Rule
The US has no federal regulation mandating SIM-free sales. Each carrier sets its own unlock policy. The main conditions as of early 2026:
| Carrier | Postpaid unlock | Prepaid unlock |
|---|---|---|
| Verizon | Automatic once device payment plan is paid off | 365 days of paid active service required |
| T-Mobile | Devices bought from 27 Jan 2026: unlocked once paid. Devices bought before that date: unlock eligible after 40 days of active service | Varies by plan |
| AT&T | Must be at least 60 days from purchase; balance paid and account in good standing | At least 6 months of active service required |
Carrier unlock policies change. Check your carrier’s current policy page before submitting a request.
United Kingdom — Locked Sales Banned Since December 2021
Ofcom banned UK mobile operators from selling locked handsets from 17 December 2021. Phones purchased after that date from EE, Vodafone, Three, O2, and Tesco Mobile are sold unlocked. Phones bought before that date may still carry a lock — contact the carrier to request a free unlock.
European Union — Largely Unlocked in Practice
EU member states each set their own rules, but competitive market pressure means most new phones sold through carriers in France, Germany, and other EU countries are sold unlocked or with short lock periods. Some carriers in specific countries still apply brief lock periods on heavily subsidised contracts; check local regulations or the carrier’s terms.
Other Regions
Policies in Australia, Canada, South Korea, Japan, Singapore, and elsewhere vary considerably. As a general rule, a phone purchased directly from the device manufacturer (Apple Store, Samsung Store, Google Store) or from a retailer rather than a carrier is more likely to be unlocked. Always verify before buying a used phone internationally.
How to Get Your Phone Unlocked
US Carriers
Contact your carrier through their website, app, or customer service line and submit an unlock request. Most US carriers process eligible requests automatically within one to two business days. You will need your IMEI and account information. Once the unlock is applied, restart the phone with a different carrier’s SIM inserted (for physical SIM locks) or attempt to add an eSIM from another provider.
The best SIM plans for the US article covers carriers and plans available once your phone is unlocked.
UK Carriers
If your phone was purchased before 17 December 2021, contact the carrier to request a free unlock. Processing times differ by carrier but are typically a few business days. Phones purchased after that date do not need an unlock request — they are already sold unlocked.
Third-Party Unlock Services
Avoid paid third-party unlock services when the manufacturer or carrier provides a free official route. Official unlocks update the device’s lock status on the carrier’s servers; unofficial methods may not work on newer devices and can void warranties.
Buying a Used Phone — What to Check
Used phones present additional risks because the SIM lock status and history may not be transparent.
Verify Carrier Lock Status Before Buying
Use the iPhone settings check or Android SIM test described above. Do not rely solely on the seller’s claim that the phone is “unlocked.” On iPhones, the Settings → General → About → Carrier Lock screen is the definitive check.
Check the IMEI Blacklist
Phones reported stolen, lost, or flagged for fraud may be added to carrier blacklists and blocked from activating on any network. Run the IMEI through a reputable IMEI check service before purchasing a used device.
eSIM and Used Phones
On a used iPhone or Android, check whether a previous eSIM profile is still installed:
- iPhone: Settings → Cellular (or Mobile Service) — look for any active eSIM line
- Android (Pixel): Settings → Network & Internet → SIMs — check for any installed eSIM
A previous owner’s eSIM profile on a phone can be deleted, but on some devices the eSIM slot may remain locked to the previous carrier if the device was not properly reset. Factory-resetting the phone before use is the safest approach when buying secondhand.
SIM-Free Status and Traveling Internationally
Using a travel eSIM or a local SIM card at your destination requires an unlocked phone. If your phone is carrier-locked, neither a physical local SIM nor a travel eSIM from a third-party provider will activate.
For an overview of all the options for staying connected while traveling — including international roaming, travel eSIMs, local SIMs, and portable Wi-Fi — see 4 Ways to Stay Connected Abroad.
If you have confirmed your phone is unlocked and want to set up a travel eSIM, Your First Travel eSIM: Step-by-Step Guide walks through the full process from purchase to first connection.
Summary
- A SIM-locked phone only connects to the carrier network that applied the lock. The restriction is software-based and removable.
- Check lock status on iPhone via Settings → General → About → Carrier Lock (“No SIM restrictions” = unlocked).
- Check lock status on Android by inserting a SIM from a different carrier, or scanning available networks.
- The UK has banned the sale of locked handsets since 17 December 2021. US carriers apply their own individual unlock policies — most require the device payment to be paid off plus a minimum period of service.
- Travel eSIMs and local SIMs abroad require an unlocked phone. Unlock your device before your trip.