What is a locked iphone

"so they go to the store and just sign up with the phone?"

Yes, they need to sign up with AT&T.

"how do they know if a person didn't steal the phone?"

They don't.

They just assigned the id numbers to the account as they do with all other cell phones.

When the new owner takes it in, they will do the same thing.

Locked means that it is carrier locked to one carrier and cannot be activated with any other carrier.

For example, ALL U.S. iphones are locked to AT&T. They cannot be activated with any other carrier, only AT&T.

Means "locked" to a specific carrier, will only activate & work on that carrier's network, will not accept a sim card from any other carrier's network nor activate on any other carrier's network. Unlocked means will activate and or work on any supported carrier's network with the appropriate activated sim card installed.

"so if we have a phone we are not using it is considered locked?"

No. You using it or not has NOTHING to do with it being locked or unlocked.

"my husband bought a iphone 4 and someone asked is the 3 locked? so we say yes?"

Only if it is locked. The iphone comes from the factory either locked or unlocked. It depends on where you bought it, and who you bought it from.

Why don't you just tell us where it was purchased?

I have a new Iphone purchased unlocked from Apple on line. The Iphone 4 type sims are interchangeable says the advertising.

When I decide which ISP to go with, will the phone lock to them via their sim card or can I switch around on Pay as you go?

If you've genuinely purchased an unlocked phone (I believe you can purchase carrier locked phones direct from Apple and many people seem to make this mistake) then it stays unlocked. So yes, you can switch between mobile providers whenever you wish. Mobile providers lock a phone to their network to ensure they get their return on their investment when they subsidise the phone.

How can I know if the iphone is locked or unlocked??, I bought an Iphone4 at the airport in SouthAfrica people there told me it´s unlocked, but when I install an inactive brand new sim card it says "sim failure".Is there any way to know if the phone is LOCKED.

Sounds like it just may be. I don't think I'd buy anything from a stranger at any airport in the world. Theres a whole host of things that could be defective about the phones inner and account points. You are more brave than I.

How much did you pay if you don't mind me asking?

Which country and carrier is it from?

In that case it is locked. All US phones are. Others can use it but they need AT&T sim.

Message was edited by: brendan002

many thanks.