A communications method, comprising: receiving, by a radio access network, RAN, node, a first message from an access and mobility management function, AMF, node, wherein the first message indicates to the RAN node to notify the AMF node when the RAN node determines that a terminal device switches from a Radio Resource Control, RRC, connected state to an RRC inactive state; determining (902, 1301), by the RAN node, that the terminal device switches from the RRC connected state to the RRC inactive state; and sending (902, 1302), by the RAN node to the AMF node according to the first message, a notification message used to notify a state of the terminal device; wherein the first message carries specified area related information, and the specified area related information is used to indicate a specified area of the terminal device; and the method further includes: receiving, by the RAN node, a further message from the AMF node, where the further message is used to request to establish the RRC connection between the terminal device and the RAN node; then instructing, by the RAN node, the terminal device to establish the RRC connection between the terminal device and the RAN node; and further, when the RAN node determines, based on the specified area related information and the location information of the terminal device, that the terminal device moves out of the specified area, sending, by the RAN node, the location information of the terminal device or the first indication information to the AMF node or the SMF node, where the first indication information is used to indicate that the terminal device already moves out of the specified area, wherein the specified area is a local area data network service area, LADN SA. receiving, by a radio access network, RAN, node, a first message from an access and mobility management function, AMF, node, wherein the first message indicates to the RAN node to notify the AMF node when the RAN node determines that a terminal device switches from a Radio Resource Control, RRC, connected state to an RRC inactive state; determining (902, 1301), by the RAN node, that the terminal device switches from the RRC connected state to the RRC inactive state; and sending (902, 1302), by the RAN node to the AMF node according to the first message, a notification message used to notify a state of the terminal device; wherein the first message carries specified area related information, and the specified area related information is used to indicate a specified area of the terminal device; and the method further includes: receiving, by the RAN node, a further message from the AMF node, where the further message is used to request to establish the RRC connection between the terminal device and the RAN node; then instructing, by the RAN node, the terminal device to establish the RRC connection between the terminal device and the RAN node; and further, when the RAN node determines, based on the specified area related information and the location information of the terminal device, that the terminal device moves out of the specified area, sending, by the RAN node, the location information of the terminal device or the first indication information to the AMF node or the SMF node, where the first indication information is used to indicate that the terminal device already moves out of the specified area, wherein the specified area is a local area data network service area, LADN SA.