There is proposed a mechanism for controlling a communication connection of a user equipment in a communication network. The communication network comprises at least a core network subsystem having at least one core network control element, and a first access network subsystem and at least a second access network subsystem. On one hand, when it is detected that at least one connection parameter of a communication connection of the user equipment can not be maintained by the first access network subsystem, a connection modification message is sent to the core network control element. The core network control element responds with an acknowledgement message the acknowledgement message comprising an instruction parameter for instructing that the communication connection of the user equipment is to be changed to the second access network subsystem being determined to having the capability to provide the connection parameter. On the other hand, when a change of a communication connection of the user equipment from the first access network subsystem to the second access network subsystem is to be performed, it is checked whether or not the cell change is executable. On the basis of the result of the checking step, a message is sent to the core network control element comprising an information element about the execution of the change of the access network subsystem.