Pressure has been put on sites with what Google is calling "faulty redirects". These occur when a user on a mobile device requests a desktop page linked to on Google and is instead redirected to the site's mobile homepage. According to Brian Klais, CEO of Pure Oxygen Labs (a mobile marketing firm), retailers with faulty redirects will suffer in their Google rankings. Google recommends webmasters follow the industry best practice of using responsive web design, namely serving the same HTML for all devices and using only CSS media queries to decide the rendering on each device.
https://developers.google.com/webmas...rtphone-sites/