The bottom-most protocol in the suite, the Wireless Datagram Protocol (WDP), functions as an adaptation layer that makes every data network look a bit like UDP to the upper layers by providing unreliable transport of data with two 16-bit port numbers (origin and destination).
All the upper layers view WDP as one and the same protocol, which has several "technical realizations" on top of other "data bearers" such as SMS, USSD, etc.
The first company to launch a WAP site was Dutch mobile phone operator Telfort BV in October 1999.
A WAP browser is a web browser for mobile devices such as mobile phones that uses the protocol.
This would be configured by the operator and could include telephone numbers, location, billing information, and handset information.
Mobile devices process XHTML Mobile Profile (XHTML MP), the markup language defined in WAP 2.0.
Introduced with much hype in 1999, WAP achieved some popularity in the early 2000s, but by the 2010s it had been largely superseded by more modern standards.
Most modern handset internet browsers now fully support HTML, so they do not need to use WAP markup for web page compatibility, and therefore, most are no longer able to render and display pages written in WAP.
It is a subset of XHTML and a superset of XHTML Basic.