Hi All readers,
It used to be that Messages could be set to a specific Location. (like the UK)
This then added the Country Code to phone numbers which had not been added in Contacts.
This was in Mac OS 10.8 through to about OS 10.10.x
Then the Apps did not have the Setting but the OS told the Messages App the location it had found for itself and the Country Code was added on that basis.
Late El Capitan and since some people have found that they have an issue when they Update of Upgrade which loses the info the OS was supplying.
By the time we get to High Sierra it seems you have to add the Country Code to the Contacts as Messages needs the info and this is now the only way to make sure it is present.
SMS does not need it as your carrier is always "Local" even if your go Roaming on the continent.
Your Apple ID is specific to you so it does not matter where you are you will get thing addressed to it.
10 or 11 digits to Phone number provides very little location info to where a Mobile phone actually is.
iMessages requires that it is located on an international basis.
9:36 pm Wednesday; October 3, 2018
iMac 2.5Ghz i5 2011 (Sierra)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
MacBookPro 15" 2016 (High Sierra 10.13.x)
Mac OS X (10.6.8),
iPhone 6 iOS 11.x and an iPad (2)
