"iMac is not a supported device" on my iphone5
Bluetooth problems.
The iPhone 5 is discoverable and is found on my imac, but the mac thinks they are paring via bluetooth, while the iphone 5 says it is not supported.
iPhone 5, iOS 6.1
That's because it isn't. iOS devices don't pair with computers, other mobile devices or even other iOS devices (unless both are using the same peer-to-peer app). iOS doesn't (and probably never will, by Apple policy) support BT file transfer.