USSD is designed to be a GSM service that allows high-speed interactive communication between the subscribers and applications across a GSM network. Unlike store and forward mechanism of Short Message Service (SMS), USSD is session-oriented such that when a user accesses USSD service. It is attractive for faster and interactive messaging services. USSD over IMS Gateway (USSI GW) is a USSD over IMS gateway for service providers, MVNO’s and wireless operators to offer USSD-based applications and services seamlessly to both GSM (2G/2G) and LTE (4G) subscribers. Subscribers may demand the speed and interactivity characteristics of USSD communication to manage their legacy services, as well as new generation LTE services, even when they are attached to an LTE network. Telenity USSI Gateway eliminates all Circuit Switched Fallback (CSFB) problems resulting from the lack of USSD support in LTE networks, and provides seamless service continuity. USSI Gateway enables subscribers to access USSD services such as balance enquiry, service configurations, etc., directly from the attached LTE/IMS network and provides similar user experience for USSD based services in 2G/3G networks. USSD over IMS Gateway (Telenity USSI GW) is a 3GPP compliant solution, which provides USSD operations support on LTE/IMS networks. It is Telenity USSD Service Center product family, USSI GW can be deployed as a standalone application server in LTE/IMS network and can be also combined with other members of family to build a fully consolidated multi-network interworking solution which simplifies operations of operators with a single point of administration and with well-defined unified integration points.