A telecommunications network including: a first radio access technology having a first radio access network and a first network core (10,12,19,32) operable to page a mobile terminal (UE 1), wherein at least one element of the first radio access technology is operable to receive mobile terminating data from the telecommunications network and to determine whether that mobile terminating data can be delivered to the mobile terminal (UE 1), and characterised by: further including a second radio access technology having a second radio access network and a second network core (10,28,30,32), wherein said first network core (10,12,19,32) and said second network core (10,28,30,32) include at least one common element, wherein the mobile terminal (UE 1) has an active state in which the cell occupied by the mobile terminal (UE 1) in one of the radio access technologies is known and an idle or inactive state when the cell occupied by the mobile terminal (UE 1) is not known but in which the last area known to be occupied by the mobile terminal (UE 1) is recorded, wherein when the mobile terminal (UE 1) is in the idle or inactive state no signalling from the mobile terminal (UE 1) to the core network is performed when the mobile terminal (UE 1) moves from one of the radio access technologies to the other of the radio access technologies, and wherein said at least one element of the first radio access technology is operable to instruct the common element of the network cores to page the mobile terminal (UE 1) using the second radio access technology. a first radio access technology having a first radio access network and a first network core (10,12,19,32) operable to page a mobile terminal (UE 1), wherein at least one element of the first radio access technology is operable to receive mobile terminating data from the telecommunications network and to determine whether that mobile terminating data can be delivered to the mobile terminal (UE 1), and characterised by: further including a second radio access technology having a second radio access network and a second network core (10,28,30,32), wherein said first network core (10,12,19,32) and said second network core (10,28,30,32) include at least one common element, wherein the mobile terminal (UE 1) has an active state in which the cell occupied by the mobile terminal (UE 1) in one of the radio access technologies is known and an idle or inactive state when the cell occupied by the mobile terminal (UE 1) is not known but in which the last area known to be occupied by the mobile terminal (UE 1) is recorded, wherein when the mobile terminal (UE 1) is in the idle or inactive state no signalling from the mobile terminal (UE 1) to the core network is performed when the mobile terminal (UE 1) moves from one of the radio access technologies to the other of the radio access technologies, and wherein said at least one element of the first radio access technology is operable to instruct the common element of the network cores to page the mobile terminal (UE 1) using the second radio access technology. further including a second radio access technology having a second radio access network and a second network core (10,28,30,32), wherein said first network core (10,12,19,32) and said second network core (10,28,30,32) include at least one common element, wherein the mobile terminal (UE 1) has an active state in which the cell occupied by the mobile terminal (UE 1) in one of the radio access technologies is known and an idle or inactive state when the cell occupied by the mobile terminal (UE 1) is not known but in which the last area known to be occupied by the mobile terminal (UE 1) is recorded, wherein when the mobile terminal (UE 1) is in the idle or inactive state no signalling from the mobile terminal (UE 1) to the core network is performed when the mobile terminal (UE 1) moves from one of the radio access technologies to the other of the radio access technologies, and wherein said at least one element of the first radio access technology is operable to instruct the common element of the network cores to page the mobile terminal (UE 1) using the second radio access technology.