As a normal user you will most likely have bought a WAP device (typically mobile phones) that either comes pre-configured from the place you bought it, configured automatically from the mobile network operator, or you will have received instructions from the mobile operator on how to configure it manually. Almost all mobile operators that offer WAP connectivity have their own WAP gateway.

The WAP device is responsible for setting up the connection to the WAP gateway, and the configured IP address of the WAP gateway will held on the WAP device. When it comes to mobile phones, most of them can be reconfigured to use any other gateway, and very few cannot.

As a WAP site owner (WAP content provider) and WAP developer you do initially not need to worry about who hosts the gateway. Once you get more advanced, you will however need to remember that different gateways work in different ways and have different types of functionality. And more important, you need to remember that in almost all cases, you do not know which type of gateway, and you have little or no control over which type of gateway that a user will use to access your site.

Chapter 1 in "Professional WAP" from Wrox