Click to call function.

Hi All

I am curretly creating an iPhone app and I want to make a button link to a phone number so when they click it it will talk them from the app to the phone and the call will go though.

If this is not possible I was wondering if you can make a number clickable, I have seen this done when you click on a number in a website it askes you if you want to call it.

Any help you can offer would be great.

Cheers

Phil