Providing Interactive Services for GSM Mobile Users with USSD
A popular way for service providers to deliver important services for GSM mobile users is to take advantage of the power of Unstructured Supplementary Service Data (USSD). Menu-driven, interactive services may include mobile account balance checking and top up along with value-added services such as sports scores, news, traffic, and weather information.
Unlike “store and forward” SMS, USSD information is sent directly from a sender’s mobile handset to an application platform handling the USSD service, which can be located either in the sender’s mobile network or in a visited mobile network. A real-time "session" is initiated between the mobile user and the USSD application platform when the service is invoked, allowing data to be sent back and forth between the mobile user and the USSD application platform until the USSD service is completed.
Dialogic® DSI Components for USSD Services
Dialogic® DSI SS7 Boards, Dialogic® DSI Protocol Stacks, and Dialogic® DSI Signaling Servers can be used to create the network elements required to develop a USSD service.
The illustration “TDM SS7 Connections Example” shows a Dialogic® DSI-based USSD platform developed using high-density PCIe signaling cards. The USSD platform uses a pair of servers and signaling cards that act as a single SS7 end point, providing availability and a high degree of fault tolerance.
Depending on the amount of USSD signaling traffic anticipated, multiple TDM Low Speed Links (LSL) (64 kbps) could be deployed. For systems with larger throughput requirements, TDM High Speed Links (HSL) could be deployed, with each signaling link giving approximately 2 Mbps of signaling throughput.
TDM SS7 Connections Example
Alternatively, the Dialogic® DSI SIGTRAN Stack could be used to connect the USSD application platform to the mobile network. The illustration “SIGTRAN Connections Example” shows a deployed service solution that uses Dialogic® DSI SUA Layer, which includes two application server processes for resilience. For SIGTRAN deployments, throughput is not limited by signaling link bandwidth as with TDM; instead, high-speed Ethernet provides bandwidth for high-performance MAP USSD applications.
SIGTRAN Connections Example
DSI Components can be chosen based on factors such as level of integration needed, expected transaction rate, and level of fault tolerance required. Because the same Application Programming Interface (API) is used across all Dialogic® DSI Components, easy migration is possible from board-based to server-based solutions or from TDM to IP (SIGTRAN) as service needs change.