Signaling gateway definition
A signaling gateway (SGW) is a network element that translates signaling messages from one protocol to another. The SGW is essentially a protocol converter allowing communication between different signaling protocols used in various telecommunication networks, like fixed line networks, mobile networks, and VoIP systems.
One of the significant roles of a signaling gateway is in the convergence of legacy PSTN (Public Switched Telephone Network) and modern IP networks (VoIP). For example, the SGW can convert SS7 (Signaling System 7) signaling, used in traditional PSTN networks, to SIP (Session Initiation Protocol) or H.323, used in IP-based networks. This allows calls to be set up, managed, and terminated across networks using different signaling protocols.
Signaling gateway in LTE networks
The SGW is an essential part of the 4G LTE network architecture, where it serves as an interface between the base station and the core network. SGW has four main tasks to ensure seamless data connectivity and service continuity for users in the LTE network:
- Data traffic. It directs the flow of data (like a router) to the correct destination.
- Handover support. SGW helps maintain a continuous internet connection when users move between areas covered by different base stations.
- Billing and lawful intercept. SGW gathers data for billing purposes (like the volume of data sent and received by a user) and can facilitate lawful interception of communications.
- Quality control. It helps manage and enforce Quality of Service rules to ensure reliable data transfer.