I cannot find an option to turn on 3g on the iphone 4s?

The 4S does not have this option; it has been removed.

so iphone 4s unlock version can support 3G network , but just it doesnt have the tunggle to turn it off? i read from some where saying that it's only support EDGE/GSM but not 3G. can you please verified.

so iphone 4s unlock version can support 3G network , but just it doesnt have the tunggle to turn it off? i read from some where saying that it's only support EDGE/GSM but not 3G. can you please verified.

It supports both. But you no longer have the option to turn off 3G and just run on EDGE. Apple decided to take this option away when they produced one phone for all carriers.

This is a problem for a lot of people who live in weak 3G areas because the phone constantly searches for 3G which I belive is another piece of the iOS 5.X battery problem.

You can turn off 3G by turning the cellular data switch on or off. If all you want to do is save battery life and receive calls, turning the setting off sets it to GSM mode. You won't be able to surf but that is the trade off.

well,

apparently when you turn data on it automatically works with the new 2 antennas system which instantly searches to the most accurate signal. when you are someplace which is a poor-signal type, then it goes back to the simple system which here in brazil shows the letter E on top of screen (cellular data).

whenever you are somewhere that has a 3g signal, it goes automatically 3g on.

hope it helped you!

the problem is, when you have a very bad 3G signal, it goes 3G and you are worse off than with the 2G....

Well, it depends on the GSM carrier you are on and the GSM they support. The unlocked iPhone 4S is not SIM locked to any carrier which means, for example, you can use the phone with T-Mobile in the US, but the iPhone4S isn't compatible with all of T-Mobile's 3G in the US, so you will be most likely limited to EDGE.

I just bought 4S and surprised to know this option is not available to manually select a network (2g or 3G). I m unable to understand smartness behind this option (can someone explain reason behind this idea)!!!

I will later check 3gpp specifications to check if this is optional or mandatory for mobile fone manufacturers to give this option.

In short I am upset from this "creativity"!!!!

to all: Apple has the beta3 update of iOS5.1 out now and it has the 3G switch in it. Update as soon as the official version is out.

"You can turn off 3G by turning the cellular data switch on or off. If all you want to do is save battery life and receive calls, turning the setting off sets it to GSM mode. You won't be able to surf but that is the trade off."

Incorrect.

"I just bought 4S and surprised to know this option is not available to manually select a network (2g or 3G). I m unable to understand smartness behind this option (can someone explain reason behind this idea)!!!

I will later check 3gpp specifications to check if this is optional or mandatory for mobile fone manufacturers to give this option.

In short I am upset from this "creativity"!!!!"

Read Thom_D's post above you:

"Apple decided to take this option away when they produced one phone for all carriers."

Not to belabor this, but the iPhone 4S isn't the only phone to not have the option to manually force the phone to 2G. The Motorola Backflip and HTC Desire, for example, do not have a toggle to manually force 2G. The iPhone 4S, like it's predecessors, auto switches between networks based on signal strength. iOS version 5.1, which is is beta, has the toggle and will most likely make its' way to the public release when that happens.