When I export I get a file WLMContacts.csv which seems to me to be OK. In Notepad, for example, I see the '+' prefix e.g. +4402081234567
However, when I import that file back to Outlook.com the phone number of all my international contacts has lost the '+' prefix!
I can't find any built-in remedy for this situation but does anybody have a bright idea that will save me editing an enormous number of contacts manually?