Link to a site that has a mobile and desktop version

My website has a link to my facebook reviews page which works well on desktop however on iphone it gets redirected to the facebook mobile site with a completely different website extension. When I change the link to the mobile version of the site it works well on iphone but a dodgy mobile version on desktop.

How can I have one link that redirects to either mobile or desktop version of the facebook website depending on the users device?