ISUP:Host application requirements

The Tmedia signaling architecture is built for high performance throughput in terms of “calls per second”. To achieve these goals, the SS7 stack located on the Tmedia hardware processes the MTP1-3/ISUP protocol layers and provides alarm and event notifications to the host application for multiple calls in parallel.

For ISUP, each call is attached to a specific circuit ID handle (which is in turn related to a specific network/OPC/DPC/variant/CIC). This ID (provided by the application upon circuit allocation) is included in every call-related event to allow the user application to know to which call it refers to. Thus, the application will receive thousands of events, each referring to different calls. Since a complete ISUP call is achieved by processing multiple SS7 messages (IAM, ACM, ANM, REL, RLC, etc), multiple messages are required for a call to reach the active state and then to be released.

These message flows, explained here, need to be controlled by the host application. Only the application possesses the information to accept/route calls according to call information (numbers, characteristics, billing, etc). Therefore, the application plays an important role in the performance of the stack. If the application is not optimized or poorly designed (e.g. synchronous), decent performance will not be achieved.