MacOS – How to stop the iMessages appearing on the MacBook Air

This is simple to accomplish if you have an iPhone to associate your phone number with your Apple ID account. I'm not aware of any way to hack, trick or cajole Apple to add a cell phone number to an Apple ID other than it going through the normal activation process on iPhone only.

1. Activate your Apple ID - http://support.apple.com/kb/TS4268
2. Open iMessage on the Mac and in preferences, set the caller ID to initiate messages from your phone number instead of your AppleID email.

As you can see, it is allowed to add more emails to an Apple ID, but the adding of phone numbers happens when you activate things from a live phone account and SMS messaging verifies that the phone number matches the iPhone.

Once that's done, Apple is happy to let your Mac or iPad or phone "iMessage" from that telephone number.

You need to put the User ID and Group entries back the way they were. If the screenshot is right, the User ID should be 502, and the Group should always be "staff" on normal accounts.

It's possible there's something else wrong as well, but this'll solve at least part of the problem. One thing to check (after fixing the User ID) is to use the Finder's Get Info to check the home folder -- in the Sharing & Permissions section, make sure the correct user account is listed. If it isn't, do not try to fix it in the Finder; there's a way to fix home folder permissions in Recovery mode that's much less likely to break anything.