We can make a call use tel protocol in Web browser with HTML code. Like this <a href="tel:012345">Make a call</a>. just we need to pass phone number tel:[phone number here]. Mostly all smartphones support this protocol. We can also have in differentiate format phone numbers. If smart phone OS won't support all the format. In windows phone we can also make a call using Phone Call Task from C# code from our Windows Phone App. We can make a call when user tap a button or some other a...