iPhone Safari phone number link with extension

Hi All,

I was wondering if anyone else knows how/if this can be done. I am writing some mobile websites for my company, and we have a phone extension list. What I want to be able to do, is have the user tap on the phone number, similar to any other phone number, but I want the extension to be added to the phone number as well, so they get through, directly to the person in the office. Anyone know how to do this?

Thanks!