Since the arrival of OS X 10.8.2, Apple has given us the option to unify the receipt of iMessages. If you have an iPhone, an iPod touch, an iPad and a Mac and registered with the iCloud service, you have at least two ways to receive iMessages: by your phone number and by the email registered on iCloud see more information on the subject in this Apple support article.
Before iOS 6 and OS X 10.8.2, messages directed to your phone number appeared only on the iPhone, while messages sent to your email (registered with iCloud) arrived on the iPhone, iPad and Mac taking into account that you have iCloud enabled on all these devices, of course.
But the trick of iOS 6 and OS X 10.8.2 is the following: if you want to receive messages sent to your number also on the Mac, centralizing everything in one place, go to Messages, go to Preferences (Preferences) Accounts (Accounts) and choose the iMessage option in the left panel. L, activate the receipt of messages by your number by clicking on the box (as in the image above). If you want others to see that you have read the message received, also check the option ?Send read confirmation? (Send read receipts).
If your iPhone number is not showing, sign out and sign in to your iMessage account again. Sign Out and then on Sign In.
If that doesn't work, go to Settings (Settings) Messages on iPhone, turn off / on the iMessage service and then go back to the Mac to see if the number appeared there. Nothing yet? On the same screen as the iPhone v in Sending and receiving (Send & Receive) and at the top touch your Apple ID. Exit the service (Sign Out) and sign in again. Okay, now your number should already be listed in OS X messages.
It's great that if you remove, add or change email addresses or phone numbers in the Messages app (Messages), a notification appears informing you of the change.
Another cool tip: centralize the output of iMessages in a single ID (email or phone number). You do this on the iPhone by going to Settings Messaging, Sending and Receiving. There, you can choose whether to start a new conversation using your phone number or email. The same thing you do on OS X, going to Preferences iMessage Accounts and choosing one of the two options.
Okay, now you receive messages on all your devices and start a new conversation using a single ID. Oh, and how it all happens via iCloud, when you receive a message the receipt of it is notified on the iPhone, iPad and Mac. But when you read the message on any of them, the notification disappears from the other devices.