You do not need to turn it on as it is software that is included as part of the latest iOS updates. You do need to ensure you are within an wifi network in order to use the service.
If you have iMessage installed you can only iMessage other iDevices that has iMessage installed on them. If someone has an iPad 2 but not with 3G but has an iPhone, then the iMessage will go there iPhone.
The only way is to buy a white coloured case.
to look tidy
iPhone 3G S = iPhone 3G + Extra's
IMessage is some thing were u can chat to people who have iPhone iPod or iPad! :)
Go to settings, sounds, and then turn it on vibrate.
between iphone to iphone via iCloud
The iphone 3g is the third generation iphone , is that what you are asking
You can only iMessage with someone else who has an iPhone, iTouch, or iPad.
If you have or can install the iMessage software on it you can but if not you can't. You can only iMessage other iDevices.
Apple invented the iPhone 3G.
Both the iPhone 3G and the iPhone 3G S support MMS with the 3.0 update.