Embodiments of the present technique can provide a mobile device and a method of establishing a connection via a core network by a mobile terminal. The method comprises receiving by the mobile terminal in a first cell an identifier assigned by a node in a first core network of a first type, the identifier comprising an identifier of the node or a group of nodes in the first core network, selecting a second cell in which service via a core network of a second type is available, and determining whether service via a core network of the first type is available from the second cell. The method further comprises establishing a connection via the second cell by transmitting a message including a first indication, the first indication based on at least a portion of the identifier, and when service via a core network of the first type is not available from the second cell, transmitting in the message a second indication, the second indication indicating that the identifier was received from a core network different from the second type, without identifying the first type of core network.