title: Can I uniquely identify a mobile device from a website?
body: <p>I have 2 questions, from a WEBSITE perspective (not a native mobile app), is it possible to</p>
  
  <p>A) Retrieve a users phone number without asking them (I'm assuming no for security reasons). This is purely with the user's consent with this service, this isn't anything sketchy. In fact, we would probably directly ask "Can you confirm this is your number?" YES/NO)</p>
  
  <p>B) If the answer is no, which im sure it is, is there a way to unique identify a user so they dont need to enter their number in manually every time (only the first time)? Do cookies work the same as they do on websites as on mobile browsers? Like could i store a permanent cookie with their number so if they visit the website on their mobile device the description changes to "Click here to change your number from <strong><em>_</em>____</strong>". We could store the phone number in our database rather than in the cookie.</p>