A Gateway GPRS Support Node (GGSN) is part of the core network that connects GSM-based 3G networks to the Internet. The GGSN, sometimes known as a wireless router, works in tandem with the Serving GPRS Support Node (SGSN) to keep mobile users connected to the Internet and IP-based applications.
The GGSN converts incoming data traffic from mobile users (via the SGSN) and forwards it to the relevant network, and vice versa. So, for instance, a Google query from a smartphone would be routed via the SGSN to the GGSN and sent on as a query to the Internet search engine, then the process would be reversed for the reply to the phone user.
The GGSN and the SGSN together form the GPRS support nodes (GSN). The GGSN is also linked into hosted services (such as voice and video) and to the billing, policy control, and user verification elements of the core network.
GGSN vendors include Alcatel-Lucent, Cisco Systems Inc., Ericsson AB, and Nokia Siemens Networks.