If you've spent any time developing WAP applications for wireless devices or have spent even less time scanning message boards and mailing lists on wireless-related online communities, you may recall that one of the most often-asked questions regarding WAP is "How can I dial a phone number via an anchor link in a document?" It often comes as a surprise to those new to WAP that this capability is new to the standard and supported by very few phones currently on the market. That's right— a technology designed from the ground up to run on mobile phones allows you to make little or no use of your phone's voice communications capabilities!
The Wireless Telephony Application Interface (WTAI) is considered to be a required part of the WAP 1.2 specification, although it made its first appearance in WAP 1.1. WTAI allows a WAP application to "initiate an interaction between the mobile and the network," as the WAP Forum documentation describes it. WAP 1.2 phones are already hitting the market, and models from major vendors such as Motorola, Nokia, and Ericsson will indeed support WTAI.
To date, WAP has been somewhat of a qualified success. The technology delivers on its promise to supply an application environment that works well across a wide variety of devices and wireless networks. At the same time, user acceptance has been far short of the numbers eagerly predicted by industry analysts in the years 1999 and 2000. Voice telephony integration has been one of WAP's "missing links," and WTAI has been developed to fill this void. In this article, I'll describe WTAI in some detail and discuss the exciting applications that can result when voice and wireless data technologies converge.