A method for setting up a communication session to a terminal device , the method, performed by an Access and Mobility Function, AMF, comprises: receiving a registration request from the terminal device , the registration request comprising data indicating a unique transaction identifier for the terminal device , the unique transaction identifier for the terminal device being a non-IMSI based user identifier having a form [ID].username@realm, wherein a portion denoted with [ID] comprises a determination of a service provider followed by a determination of a task defined to a subscription , interacting communicatively with a Network Slice Selection Function, NSSF, for assigning , on a basis of the unique transaction identifier, a network slice of a mobile communication network providing communication service to the terminal device , the network slice being accessible with a session management function initiated for the terminal device , interacting communicatively with a Policy Control Function, PCF, for assigning a charging and policy scheme to be applied to the terminal device determined on a basis of the unique transaction identifier, the charging and policy scheme being accessible with an application function initiated for the terminal device, in response to the assigning of the network slice and the assigning of the charging and policy scheme for the communication session generating an acknowledgement to the terminal device , the acknowledgement indicating an acceptance to the registration request for causing a setup of the communication session by the terminal device between the terminal device and the application function through a user plane function. receiving a registration request from the terminal device , the registration request comprising data indicating a unique transaction identifier for the terminal device , the unique transaction identifier for the terminal device being a non-IMSI based user identifier having a form [ID].username@realm, wherein a portion denoted with [ID] comprises a determination of a service provider followed by a determination of a task defined to a subscription , interacting communicatively with a Network Slice Selection Function, NSSF, for assigning , on a basis of the unique transaction identifier, a network slice of a mobile communication network providing communication service to the terminal device , the network slice being accessible with a session management function initiated for the terminal device , interacting communicatively with a Policy Control Function, PCF, for assigning a charging and policy scheme to be applied to the terminal device determined on a basis of the unique transaction identifier, the charging and policy scheme being accessible with an application function initiated for the terminal device, in response to the assigning of the network slice and the assigning of the charging and policy scheme for the communication session generating an acknowledgement to the terminal device , the acknowledgement indicating an acceptance to the registration request for causing a setup of the communication session by the terminal device between the terminal device and the application function through a user plane function. <EOS>