I am working on an idea I have for a mobile app, and I’m trying to figure out the best sign-up process. I want the app to sync with the user’s contact list just as WhatsApp does: i.e. it identifies all the contacts in your phone book that have WhatsApp installed.
With WhatsApp, a user signs up with their mobile phone number and then uses a passcode to verify.
This simple sign-up process seems to work really well, but I wanted to get some thoughts on how important other things are, like username/email/password/login with social networks?