iOS 5: iMessage

A big part of iOS 5 (s aapl) is iMessage, Apple’s new unified messaging platform for communicating between iOS 5 devices. It’s a great tool, but users new to the tech might have a hard time figuring out how to get started, since it’s tied so closely to the existing Messages app. Here’s how it works.

Setting up iMessage

To clear up one point of confusion I’ve been frequently asked: While the service is called iMessage, the actual app where you use it on iOS is called Messages.┬áTo setup iMessage, go to Settings and then Messages. Make sure you are signed in with your Apple ID email address. Tap Receive At and make sure your phone number (on the iPhone only) and relevant email addresses (on iPad and iPod touch) are correct.

You can set up multiple email addresses at which to receive the same iMessages. When you add a new email address, a verification email will be sent to that address. When you click on “Verify Now” in the email, you will be sent to an Apple site where you enter your Apple ID and password to verify the new address. I have both my and (s goog) addresses registered in iMessage.

Using iMessage

To take full advantage of iMessage, all participants need to be running iOS 5. To send a message, in Messages press the New Message icon in the upper-right-hand corner of the app.

Start typing your recipient’s info, and the field will auto-fill with possible choices in a manner similar to the Mail app. If you’re sending the message from your iPhone, the Send button will turn green if it will be sent as an SMS, or blue for iMessage. On the iPad, if the address you’re trying to send to isn’t registered with iMessage, you’ll get an error message, like the one below.

Limitations of iMessage

To ensure your Message is received on all your connected devices, you must have them sent to your Apple ID email address. In limited testing, if someone sent me a test message to just my phone number, I only got the text on my iPhone. However, if they sent the message to my address (which is my Apple ID address), I got it on all devices. This is because Apple can’t associate your phone number (assigned by your carrier) with devices other than your iPhone. Also, if you’ve added multiple email addresses to the “Receive At” setting on one iOS device, you’ll need to make sure you add them manually to any other iOS devices you own, too, if you want to receive messages at that address on all devices.

While AT&T (s t) has changed their SMS plans, most likely in preparation for people lowering their text message plans, for me, my SMS usage won’t change. Most of the people I text with don’t have an iPhone. Still, since it operates automatically behind the scenes, detecting who can and can’t receive iMessages, there’s definitely no harm in having it enabled, regardless of who you message with.