Wireless communications systems offer a variety of services to subscribers such as interconnect calling, short message service, packet data communications and push-to-talk (PTT) communications. Each wireless communications system operates using one or more wireless technologies such as code division multiple access (CDMA), global system for mobile communication (GSM), time division multiple access (TDMA) or Advanced Mobile Phone Service (AMPS).
Many wireless communications systems facilitate communications between a wireless application server and a client application resident on the wireless subscriber unit. For example, PTT services (also known as a walkie-talkie or dispatch services) are currently offered as an Internet protocol (IP) application served by a PTT server. Various frameworks exist for facilitating application services across a wireless network, including the Advanced Intelligent Network (AIN) and IP Multimedia Subsystem (IMS) standards.
However, as a mobile subscriber roams between wireless networks having different architectures, and operating under different protocols and standards, providing seamless access to a given wireless application becomes problematic. For example, many wireless communications systems implement proprietary standalone applications. Other wireless communications systems provide an IMS-based application architecture. As deployment of IMS becomes more prevalent in wireless networks, the mobility of subscriber terminals becomes problematic when there is need for carriers to provide seamless access to applications across networks due to a mix of IMS-based and stovepipe-based application architectures.