tel links callto fallback

tel_to_callto.js

$('a[href^=\'tel:\']').each(function() {
   var target = 'call-' + this.href.replace(/[^a-z0-9]*/gi, '');
   var link = this;

   // load in iframe to supress potential errors when protocol is not available
   $('body').append('<iframe name="' + target + '" style="display: none"></iframe>');
   link.target = target;

   // replace tel with callto on desktop browsers for skype fallback
   if (!navigator.userAgent.match(/(mobile)/gi)) {
       link.href = link.href.replace(/^tel:/, 'callto:');
   }
});