Usability 
Getaway is a new hotel search engine, primarily for South Africa but with some listings for other African countries and for India.
Listings include a photo, description and the hotel's phone number and email. While the listings are useful, it might be hard to actually find or even contact the hotels as they don't include a street address and the phone numbers and email addresses are plain text rather than click-to-call or mailto: links.
It's such a simple thing for web designers to make a phone number and email clickable. No fancy back-end scripting is required, just a link:
<a href="tel:1-800-555-1212">1-800-555-1212</a>
<a href="mailto:nobody@example.com">nobody@example.com</a>
Granted, "tel:" and :mailto: are not supported by all phones and there is an alternate click to call format that some older phones require . But tel:or mailto: do work on most modern handsets and including them shouldn't break anything on the ones that don't. Making the phone number or email address clickable improves usability immensely and creates a simple but effective call to action that will help drive business to the target. Source: Oh! Mobile Directory