You’re not wrong but I don’t exactly agree! Your phone is a facet of your social network… It’s the people you have a close enough connection with (by a mixture of geography and sociability) to warrant keeping their details handy. It’s higher signal to noise than your mailbox - and the connection strength will likely be greater - but it’s not the be all and end all. Example: I occasionally need to reach my bank in an emergency so I have their number on my phone; my cousin lives in Australia so I have his email address but not his phone number. As the distance between mobile and static devices lessens the distinction will become irrelevant though and then the differentiation will be on context. Who do you contact during working hours? Who do you respond to on Twitter? Who did you sit next to at that conference? When you start to aggregate that sort of data the subtlty of your network ought to be easier to intelligently tap.