Carrier lock
Carrier lock is software-level binding of a phone to one carrier — it refuses to activate on other networks until unlocked. Carrier-financed phones are usually locked until the financing is paid off.
A carrier lock (also called SIM lock or network lock) is a software restriction that binds a phone to one specific carrier's network. The phone refuses to register or activate when you try to use a SIM/eSIM from a different carrier. Carriers use locks to protect their financing investment — if they sold you a $1,200 iPhone for $0 down on a 36-month plan, they want to make sure you stay with them long enough to actually pay it off.
How locks happen
- Bought via carrier financing (Verizon Device Payment, T-Mobile EIP, AT&T Next): locked until the device is paid off. Postpaid carriers are required by FCC rules to unlock after 60 days of paid service for devices purchased outright; financed devices unlock when financing completes.
- Bought outright from a carrier: usually unlocked at purchase or after a brief 60-day period.
- Bought from Apple, Google, Samsung directly: unlocked from day one. Always.
- Prepaid carriers (Cricket, Metro, Boost): may hold locks for 12 months from activation regardless of whether you paid the device off. Read the fine print.
How to check if a phone is locked
The simplest test: insert (or eSIM-activate) a SIM from a different carrier. If the phone refuses to register or shows "SIM not supported," it's locked. If it activates fine, it's unlocked. iPhone users can also go to Settings → General → About → Carrier Lock — if it says "No SIM restrictions," you're unlocked.
How to get a lock removed
Call the carrier that locked it. They're required by FCC rules to unlock postpaid devices that have been on their network at least 60 days and have no outstanding balance. The unlock is usually free for postpaid; some prepaid carriers charge a small fee. The unlock usually applies within 24 hours. After it's unlocked, you can BYOD to any other US carrier.