SSTM: A State Based IMS Service Triggering Mechanism

In the current IP Multimedia Subsystem (IMS), the service triggering is mainly executed by the Serving-Call Session Control Function (S-CSCF) according to the information included in the initial Filter Criteria (iFC) which is stored in the Home Subscriber Server (HSS). In this paper, after analyzing the defects of the current mechanism, we propose a new service triggering mechanism: State based Service Triggering Mechanism (SSTM). It aims at triggering services more dynamically in real time, and decreasing the load of the S-CSCF. In this mechanism, we mainly introduce a User Service Triggering Management entity (USTM) which is in the charge of service triggering according to the service state information returned by ASs. After all of the improvements we have done, this mechanism can easily meet the requirements of providing lots of rich and colorful IMS services, and can effectively prevent the weak point of current IMS static service invocation.