Hi there, I took a look at your blog and it looks like you're using the Twenty Eleven theme for Wordpress. If I'm not mistaken, there's not a way to create a clickable phone number within the header image because the header image is just a flat .jpg that is already a link back to your blog's homepage. There's a few plugins available that would allow you to add a clickable phone number to your page, but not in the header image. That being said, would you be open to a design that does not incorporate a clickable phone number?

Yes I am open to a design that does not incorporate a clickable phone number.