If your website doesn't have a mobile version, you must correct that! Too many sites either display poorly on mobile devices, or even worse, don't display at all. Recently I tried to visit a site on my iPhone, but it opened up to a blank white page; when I got back to the office I browsed to the site on my laptop and found that it's built entirely on Flash. That results in nothing to display on the iPhone!
Luckily, when I initially tried to visit the site I wasn't looking to buy or researching a company I may want to do business with; if that had been the case, they would have had a lost sale.