Mobile access terminal with local call session control function

A computing device, computing system, method, and medium are provided for utilizing a local Call Session Control Function (CSCF) server located on a mobile access terminal to facilitate access to application services hosted by an application server. An application-service client corresponding to the application server is instantiated on the mobile access terminal and interacts with the local CSCF server via a local control interface. The local CSCF server includes features of a Serving Call Session Control Function (S-CSCF), and thereby enables authentication, interoperability testing, and control functions to be performed in the operating environment on the MAT. The local CSCF server interacts according to a predetermined relationship with an S-CSCF on the IMS network to facilitate access to application services.