A Mechanism for Handling Internal Threats of IMS Based Push to Talk and Push to Multimedia Service

Capabilities like Instant Messaging (IM), real-time video transfer and file transfer converts the Push to Talk (PTT) Service into a new one, known as Push to Multimedia (PTM). In PTT and PTM an authenticated user can be deleted from the session by the session administrator (initiator). Deletion of an authenticated user by a single authority may results in dispute among the remaining authenticated members. So in this paper we present a distributed mechanism to delete an authenticated user (who starts to act maliciously after authentication) from an ongoing session. Moreover a user may use the floor for the long period of time. No mechanism is defined to preset the maximum time for the floor use in a single turn. In this paper we also give a mechanism to define the maximum time for floor use at the start of the session. This time can vary from user to user. These features on one side secure the PTT and PTM service and on the other side enrich these services.