In its current form, adding a bookmark on a mobile device or iPad is impossible. You need to find a way to let users do that. You also need to add a way that people can delete there accounts since you're asking for our phone numbers
One solution is to expose the JavaScript bookmarklet snippet on the page. Then the user can bookmark a dummy page, like the one they're currently on, then edit the URL of the bookmark to the JavaScript.
Some popular bookmarklets are being collected on the page below with that purpose in mind.
