An access and mobility management function (AMF) receives a registration request for a wireless device. The AMF sends, to a network repository function (NRF) and in response to the registration request, a discovery request for an address of a session management function (SMF). The discovery request comprises network slice isolation information for at least one network slice. The AMF receives, from the NRF and based on the discover request, a discovery response comprising the address of the SMF. The AMF sends, to the SMF, a session create request to create a session for the wireless device.