A method of establishing a Packet Data Unit, PDU, session between a User Equipment, UE (51; 600), and a data network identified by a Data Network Name, DNN, in a telecommunication network. The telecommunication network comprising an Access and Mobility Function, AMF (56; 66; 500), and a Policy Control Function, PCF (60; 700). The method comprising the steps of receiving (3; 310), by the AMF (56; 66; 500), a registration request initiated by a UE (51; 600) for registering the UE (51; 600) in the telecommunication network; retrieving (16; 320), by the AMF (56; 66; 500), from the PCF (60; 700), PDU session establishment information, wherein the step of retrieving (16; 320) is triggered upon receiving (3; 310) the registration request; receiving (16b, 330), by the AMF (56; 66; 500), from the PCF (60; 700), PDU session establishment information comprising one or more DNNs to which PDU sessions are to be established by the UE (51; 600), and transmitting (21a; 340), by the AMF (56; 66; 500), to the UE (51; 600) an instruction comprising one or more DNNs for establishing at least one PDU session between the UE (51; 600) and at least one DNN of the one or more DNNs upon receipt of the instruction. Complementary methods and equipment arranged to perform such a method are also presented.