DSCIM: A Novel Service Invocation Mechanism in IMS

In the service invocation mechanism of current IMS (IP multimedia system) network, the serving-call session control function (S-CSCF) invokes each application server (AS) sequentially to perform user´s service profile. This mechanism makes SIP request be forwarded excessively among the S-CSCF and application servers (ASs), so it is easy to result in the heavy load of the S-CSCF entity and long call set-up delay. Service capability interaction manager (SCIM) is an entity providing service invoking capability and service interaction management, which is out of standards at present. This paper proposes a novel distributed SCIM (DSCIM) service invocation mechanism within IMS service provision architecture. It aims at reducing the call set-up delay in IMS service layer along with decreasing the load of the S-CSCF entity by invoking each AS consecutively without signaling being forwarded back to the S-CSCF. We model the service invocation mechanisms through Jackson network and the simulations of different scenarios verify that DSCIM service invocation mechanism can effectively reduce call set-up delay of the network and decrease the load level of the S-CSCF.