You can add the phone number as one Top Menu Item without any link or you can edit the Logo Image and can add the phone number there.
You can add the following in the Custom Code within Header Area of Small Business Options and change the values as expected:
Code:
<style>
.featured-box { display: none; }
body { font-family: Arial,Helvetica,sans-serif; }
#smallbusiness-main-menu, h1, h1 a, h1 a:visited, h1 a:hover, h2, h2 a, h2 a:visited, h2 a:hover, h3, h4, h5, h6 { font-family: ‘Coda’,cursive,sans-serif; }
</style>