The chicken-and-egg problem is really what matters here. Your 'address' is never going to cover all services that people use from day one, so my friend would ha

The chicken-and-egg problem is really what matters here. Your 'address' is never going to cover all services that people use from day one, so my friend would have to keep that number around + my other contact info that are not covered. Similarly I'd have to keep in my contacts all the information regarding people who are not registered to your service. From my point of view as a user, this is just another line in the contact card...