The invention provides a method of controlling LA-based update procedure in a mobile radio communications network, and including the step of determining the reason for the LA-based update request, and varying connection procedures upon receipt of such request and responsive to the determination, and so can also provide a mobile radio communications network device arranged for operation in the network including plural terminal devices, the network device being arranged to forward to a target network device an indication of reasoning for a LA-based update procedure (during CSFB to the legacy system for example). Further the invention can also be embodied in a mobile radio communications network target device arranged for operation in the network including plural terminal devices and further arranged to monitor for an indication from a network device for reasoning for a LA-based update procedure, and further arranged to vary a connection procedure responsive to the said monitoring.