I love the way Mobility does iphone/smartphone versions right out-of-the-box. This is working really well for us.
I have used an <a href="tel:xxx">xxx</a> link on one page which provides a very simple way for iphone users to call. But in non-phone browsers it is a dead link.
Do you have any tips on how to show certain content to certain browsers only?
Unfortunately, I think it's not possible. You entered the phone link in Joomla (into a content article, I guess), but there's no option in Joomla that will show different content depending of user's device.