SIP-Enabled Gateway MSC: Linking WiFi Hot Spots with 2.5/3G Networks

WiFi technology has been embraced by a large number of consumers at home and in the vertical markets such as enterprises, education, and healthcare. WiFi is experiencing extremely rapid growth on all fronts, including the number of public hotspots, the number of devices with built-in support for WiFi, and the number of upstart WiFi carriers. Cellular service providers have recently jumped on the WiFi bandwagon. Initially, the main driver for WiFi deployment has been wireless access to internet and data services. However, it is only natural to wonder if it can be utilized to offer packetized voice service, particularly since the end devices will be supporting 802.11 as a data interface. Although some limited deployment of Voice over WiFi exists today in enterprises via IP PBX, voice over WiFi has not yet become mainstream in public networks. It is a compelling idea to offer the best features of both WLAN & cellular networks to users by combining the small coverage area but low cost & high data rate of WLAN’s with the large coverage area of 2G, 2.5G, and 3 G cellular networks (albeit at lower data rates and higher costs compared to WLAN). Interworking WLANs with cellular networks expands the coverage area and brings immediate value to users with dual band cellular and WiFi handsets. The main objective of this paper is to examine the issues related to interworking of VoIP over WiFi with cellular networks. A traditional Gateway MSC bridges between PSTN and Cellular networks. A particular focus of this white paper is on the important role that a SIP-Enabled Gateway MSC can play in bridging between the IP and circuit switched network and argues that the Gateway MSC is in the best position to most economically deliver a service that spans across technologies.