iphone 3g 16g upgraded from 3 1 2 to iOS 4.

Well,Actually, if you don't mind the cumbersome process of jailbreaking and unlocking after upgrading,Then the upgrade is still good,But when you ask what jailbreak is,I suggest you don't upgrade,Jailbreak has been unlocked even if it's a very detailed **tutorial for novices It's still very troublesome,And there will be some problems in the middle,It will make you very big,If you really want to upgrade,It's recommended to look at the tutorial before starting,What I want to say is,3G upgrade can be some cards, Personally, it's better not to upgrade.

Jailbreak refers to the opening of the user's operation permissions, so that the user can erase the running state of any area at will, only after the jailbreak is successful, the iPhone (1) file system is in the read-write (RW) state, you can install and run third-party programs and plug-ins that have not been officially certified. The software is either rejected by the Apple Store for some reason (usually because it violates Apple's rules) or the developer does not have a Mac, or the author refuses to pay $100 to publish their work. After jailbreaking, you will be able to use these software.

The biggest difference between iPhone's iOS and other mobile phone systems such as Nokia's Symbian, Google's Android, etc., is that the latter two are open user permissions, while iOS user permissions are extremely low. To put it simply, the user permission of the latter two users is RW (read and write), while the user permission of iOS is only R (read only). As a result, iOS users can only use apps that have been verified by Apple (purchased in the Apple Store), and other behaviors cannot be changed to the system.

The advantage of iOS is that compared to other systems such as Nokia Symbian, Android and other ISO systems, the stability is extremely strong and the crash rate is extremely low. Anyone who has used Nokia Symbian should have experienced a crash and battery pulling. ）

To put it simply, it is possible to install pirated software after jailbreaking.

Hope it helps.

It seems that the shutdown can't be charged, if you want to downgrade, just restore to the factory settings, it's OK, and after connecting the phone through iTunes, there is a factory reset column in your device.

iPhone3G can only be upgraded to iOS up to the highest level

iPhone3GS can be upgraded to iOS up to the highest level

Antique iPhone, collect it well.

1。This one of yours is iPhone3G, not iPhone3GS, the minimum factory version of 3GS is, so there is no system version of 3GS (please refer to the system version of iPhone4 when iPhone4s is released).

The flashing machine is unlimited. You can brush. You can also brush the highest version of iPhone3G at one time, but one factor that needs to be taken into account is unlocking.

The iPhone with a locked version cannot be unlocked directly. If you want to unlock it, you have to flash the baseband chip. There's a lot more to be involved here.

I won't go into details. Another factor is that the iPhone 3G runs very slowly under the version. I suggest you brush this version best.

The vast majority of the current iPhone 3G is or version.

3。Upgrades do not result in fewer features. The higher the version, the more features it will have. However, the system load will also become larger, and with it, the mobile phone will run slower. This is the case I mentioned above.

You can upgrade directly to the latest version, and now the latest version is.

If you upgrade, all the apps will be gone, you can back up it on your computer, re-jailbreak and sync after the upgrade.

There will be no fewer features, and there will even be a lot of new ones.

The best thing to do is to level up and listen to me.

iPhone5Which group of this model supports3G,If good Zen fruit uses a mobile card,The model can only use 2G network,In addition, the telecom version does not support mobile cards。

How to set up 3G:

1. Find the "Settings" icon on the iPhone home screen and tap to open it. <>2. In the settings list, click to open the "Cellular Network Plum Socks" option. <>3. Then in the cellular network settings, tap the switch on the right side of 3G to turn it on.