How to check if iPhone 3GS is factory unlocked?

[reetus]

I am having a small query regarding which i am curious. I actually i have bought a used iPhone for my use and let me tell you that the device of mine is not having any problem. It is not having any installed installed. I have checked and know that the i am using the iPhone OS 3.1.2. All i wanted t know that is there any way by which i will come to know that the device is factory unlocked? Thank you.

[Bon-Z]

There is only one way to know whether your device is unlocked or not. For that you just have to take out your SIM card and then insert any other SIM card to it. If it is reading the another SIM card then it is unlocked with the factory. So try this out and see whether your device is unlocked or not. Hope this will work.

[urgaffel]

There is one more way by which you can come to know about your device's unlocking. Just connect your device to the iTunes and then see whether you are getting any notification about the unlocking or not. I am having the same issue which you are going through but let me tell you i have get the notification in the iTunes.

[Simond]

The best way to know about your device is unlocked or not is to contact the Apple. For that you have to visit the nearest Apple Store and ask them about then device of yours. They will check the device of your and will let you know whether it is working great or not. So try the same and see whether it is working or not.