METHOD FOR AN IMPROVED HANDLING OF AN INTERNET PROTOCOL MULTIMEDIA SUBSYSTEM CONVERSATIONAL SERVICE OF A USER EQUIPMENT, SYSTEM, PUBLIC LAND MOBILE NETWORK, CALL STATE CONTROL FUNCTION NODE, PROGRAM AND COMPUTER PROGRAM PRODUCT

摘要

The invention relates to a method for an improved handling of an internet protocol multimedia subsystem service of a user equipment in the context of an ongoing session, wherein — a call state control function node, and — an application server is being used to enable or provide the internet protocol multimedia subsystem service of or to the user equipment, wherein the user equipment, in order to receive the internet protocol multimedia subsystem service, is able to either use a first public land mobile network or a second public land mobile network by using either a first access network and a first serving gateway node of the first public land mobile network or a second access network and a second serving gateway node of the second public land mobile network, wherein, while the user equipment being connected to the first access network of the first public land mobile network and the session being ongoing, the method comprises the following steps: — in a first step, an inter-public land mobile network handover of the user equipment occurs or is triggered such that the user equipment is or is to be connected to the second access network of the second public land mobile network instead of being connected to the first access network of the first public land mobile network, — in a second step, subsequent to or partly overlapping with the first step, a current public land mobile network information is transmitted, by the call state control function node to the application server, the current public land mobile network information indicating, to the application server, that the user equipment uses the second access network of the second public land mobile network instead of the first access network of the first public land mobile network.