A method for operating a session control entity configured to control a data packet session of a user in a cellular network. A policy request is transmitted to a policy control entity of the cellular network requesting at least one policy rule for the data packet session. A policy response is received including the at least one policy rule for the data packet session and including a request to provide information about an address translation carried out in a user plane on the data packets of the data packet session. Rules for handling the data packet session are transmitted to a user plane entity configured to handle the user plane of the data packet session. The rules include a translation detection rule by which the user plane entity is requested to inform the session control entity about the address translation that has taken place in the user plane.