I am wondering if there is a proper way of identifying a users identity? I am looking for some kind of solution as to verify the user-identity via his phone-number, so a user would have to confirm his registration by entering a "code" which is send to him via SMS. Something similar as Google is providing. Or probably some other solution, e.g. a user needs to provide his Passport-ID into the registration-form and is required to upload a copy of his Passport ? Does any of you guys have any ID-verifiction in use at your Forums? What makes sense in this regard in terms of practicability and also in terms of cost? Many thanks!