The presumption in the Linked article is that the Apple ID has been added to the iPhone before it is added elsewhere including the Mac version.
If you have not already done so then add the ID to the iPhone.
If after a few minutes the Mac version has not had the pop to say the iPhone is using it's Number and the Apple ID then restart the app on the Mac.
iMac 2.5Ghz 5i 2011 (Mountain Lion 10.8.3)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
Couple of iPhones and an iPad
"Limit the Logs to the Bits above Binary Images." No, Seriously