Because WAP applications are most commonly run on mobile phones, common sense would dictate that there would exist the capacity to simply select a link to dial a number (kind of a "direct-dial URL"). Surprisingly to some, WAP didn't officially support this feature until version 1.2 introduced the Wireless Telephony Applications Interface (WTAI). The WTA Interface allows WML/WMLScript applications to actually interact with the telephony-related functionality of a mobile phone and a wireless network. For instance, WTA will do all of the following:
Allow numbers to be dialed via the selection of a hyperlink
Provide for programmatic access to a phone's address book
Send DTMF tones programmatically
WTAI defines a new URI (wtai://) along with specific libraries and functions to be called within the URL. For instance, to define a link that will dial a number (for instance, 1-800-555-1212) when selected, use the following syntax;
WTA capabilities will be included with WAP 1.2-compliant phones, which should begin hitting the market in spring, 2001.