Apple introduced its chat service iMessage with the launch of iOS 5. iMessage is a text messaging chat similar to internet messaging AIM, ICQ, Facebook chat or the ever popular WhatsApp app. The difference is iMessage is integrated into the Messages app which is used for SMS/MMS.
When you send a text message, the message app will check if the recipient is using iOS 5 with iMessage enabled. If yes your text will be send out via iMessage. If not the text will be send out using regular SMS via telco. iMessage is a free service, and this could potentially saves you some telco SMS charges.
When you upgraded to iOS 5, iMessage is enabled when you enable iCloud. To check, open the Settings app and look for Messages and make sure the switch is turned on.
You can find out if your text will be send out using iMessage or SMS while composing your text. iMessage text will be blue in color and the text entry field will display “iMessage”. For SMS message, the text is green in color and the text entry field will display “Text Message”.
iMessage is not limited to iPhone, the Message app is also available on iPad and iPod touch. When you use the Message app on iPad or iPod touch, you need to enter the recipient’s email address when composing a text. Phone number will not work.
In order to receive iMessage from someone using iPad or iPod touch, you need to setup an email address for your iMessage. Under Settings>Messages, tap the “Receive At”.
Select to enable to use Apple ID for iMessage. This will add the email address for your Apple ID as an address for “You can be reached for messages at”. Your friends can then iMessage you using the email address.
With iMessage, Apple merged the traditional telco SMS and Internet chat within the same Message app. A brilliant move that brings cost saving benefit and convenience to iOS users.