Design and Implementation for SIP-based Push-to-Talk Services over 802.11 Networks
Push-To-Talk (PTT) is a service that allows users using mobile phones in a way like walkie-talkie. All big telecommunication vendors and operators consider PTT an emerging application. 3GPP and OMA (Open Mobile Alliance) regulate the PTT specifications on the basis of Session Initiation Protocol (SIP) to assure interoperability. However, current PTT services are dedicated to cellular phones. The users would like to realize PTT services with popular 802.11 wireless networks and VoIP services. Thus, in this paper, they implement a PTT system that works in 802.11 networks. Moreover, they interconnect it with GPRS network to compare the performance in-between these two heterogeneous networks.