13.5 Applications in WAP

13.5.1 Multimedia Messaging Service

Multimedia messaging service (MMS), as the name implies, provides multimedia content between communication endpoints in a messaging context. For example, the user may receive a greeting card with a nice picture and a recorded voice messages wishing him well. Multimedia messaging service is viewed as a non-real -time service, and it seems like an extension of the SMS service in that SMS handles only limited text, while MMS is expandable to a wide variety of services from traditional e-mail to content-rich chat services. However, future versions of MMS may support real-time messaging like Instant Messaging and chat services.

Addressing in MMS can be done in the form an Internet e-mail address like [e-mail]. Additionally, MMS can support addressing with the MSISDN ([e-mail]), which is used in cellular networks for backward compatibility.

13.5.2 Wireless Telephony Applications

Wireless telephony applications (WTAs) are defined as part of WAP specifications to allow access to telephony functionality. WTA provides tools for value-added telephony applications and provides a bridge between wireless telephony and data. WTA applications are developed using WML and WMLScript and are defined as a WAE user agent. WTA is covered in details in the WAP specifications.

13.5.3 Push Services

Wireless users can subscribe to push services which can be delivered to the user asynchronously when a preferred event happens. Normal uses of push services are calendar reminder services, voice mail or message indicators, and other information reporting services.

WAP specifies push architecture for the support of push services in the WAP network. Push architecture involves a push application server called the push initiator (PI) and a push proxy gateway (PPG) and the wireless devices. Over the air, a special protocol, called Push Over-the-Air Protocol, to communicate between the PPG and mobile device is used. A Push Access Protocol (PAP) is used between the PI and the PPG.