A carrier-locked phone works only with the network that sold it; an unlocked phone takes a SIM from any compatible network. Neither says anything about who owns the phone or what it is worth: a brand-new flagship can be locked and a years-old budget phone fully unlocked. Here is what the lock restricts, how to tell which one you have, what changes once it is removed — and, because carriers’ holiday deals are where most locked phones come from, what to check before you take one.
What “carrier-locked” means
A carrier-locked phone will only accept a SIM card from the one network it was sold with (or that network’s family of brands). Insert a SIM from a different carrier and the phone will refuse to make calls, send texts, or use mobile data — usually with a message like “SIM not supported” or “invalid SIM”.
Carriers do this because many phones are sold at a discount tied to a contract or an installment plan. The lock is the carrier’s assurance that the phone stays on their network until that commitment is honoured. It’s a restriction on the hardware, not a statement about who owns the phone — you own it either way, locked or not.
What “unlocked” means
An unlocked phone accepts a SIM from any compatible carrier, anywhere. It might have started life locked and been unlocked later — through the original carrier, or a service like ours — or it might have been sold unlocked from day one, which is how many phones bought directly from a manufacturer are sold.
How to tell which one yours is
- iPhone: Settings → General → About → Carrier Lock. “No SIM restrictions” means unlocked; anything else names the lock.
- Android: Settings → Network & internet (or Connections) → look for a SIM lock or network lock status; wording varies by manufacturer.
- The universal test: borrow a SIM from a friend on a different network. If it connects, you’re unlocked.
- A phone you don’t have in your hand: an IMEI check reports the carrier and lock status on record.
What actually changes once you unlock
| Carrier-locked | Unlocked | |
|---|---|---|
| Works with your current SIM | Yes | Yes |
| Works with another carrier’s SIM | No | Yes |
| Works with a local SIM abroad | No | Yes |
| Typical resale value | Lower — smaller buyer pool | Higher — see the benefits guide |
Unlocking doesn’t disconnect the phone from cellular networks or remove the need for a SIM and a plan; it simply stops the phone refusing other carriers’ SIMs. It also doesn’t add network bands the hardware lacks, so check that the model supports your new carrier before you switch. For the full list of what improves, see the benefits of unlocking your phone; for how the unlock itself is carried out, how carrier unlocking works.
Holiday phone deals: locked or unlocked?
A phone “free with a plan” or “on us over 36 months” is nearly always locked, and the lock stays until the carrier’s own conditions are met — usually the balance paid off plus a minimum time on the account. Read the deal’s small print for three things before you accept it: how long the credits run, what happens to the balance if you leave early, and the carrier’s unlock rule. Those rules, as the carriers publish them today:
| Carrier | When it unlocks a phone it sold (own rules, read Oct 2026) |
|---|---|
| AT&T | Bought more than 60 days ago, paid in full, no lost/stolen/fraud report, bill not past due; AT&T Prepaid 12 months of paid service. |
| T-Mobile | Postpaid: 40 days active on the line and paid in full. Prepaid: 365 days since activation, or more than $100 in refills per line plus 14 days. |
| Verizon | Phones activated from January 27, 2026: postpaid once paid in full; Prepaid after 365 days of paid, active service (on request). Activated earlier: 60 days. |
| Cricket | 365 days of paid service for a phone bought on or after July 1, 2026; six months for one bought before. |
- 1Know the model, not the deal nameSettings → About gives the exact model; variants of one phone differ in network bands. Check the destination carrier’s compatibility page before buying a phone to take there.
- 2Gifting a used phone? Check its IMEI firstDial *#06# on the phone (not the box) and run an IMEI blacklist check and a carrier check: a phone reported lost or stolen is refused by every network, whatever the lock, and no one but the carrier that placed the report can remove it.
- 3Count the lock into the priceA locked phone resells for less and can’t take a local SIM abroad until it is unlocked. If the deal’s saving is smaller than that cost to you, an unlocked phone at full price may be the better buy.
- 4Keep the paperworkThe receipt with the purchase date and the account it was bought on are what the carrier asks for when you request the unlock later — and what the next owner will ask for.
Why carriers lock phones at all
The economics are straightforward: a carrier that sells a phone at a discount, or lets you pay it off over time, wants some assurance it keeps earning your service revenue until that cost is recovered. The lock is that assurance. It’s also why the lock is tied to the phone paying off its balance and staying in good standing — see is my phone eligible for unlock for exactly what that involves.
