Abstract: A communication method includes after a session management function network element establishes, for a terminal device, a protocol data unit session that is in a first network and that includes a first quality of service flow, and when a terminal device is handed over from the first network to a second network, if it is determined to map the first quality of service flow to a first bearer in the second network, the second message that includes an identifier of a first accounting session corresponding to the first quality of service flow and information about the first bearer may be sent to an authentication, authorization, and accounting server such that the second message indicates the authentication, authorization, and accounting server to update the first accounting session.

Abstract: A charging method, a network device, and a system, where the method includes performing, by a policy and charging enforcement function (PCEF), online charging for user equipment (UE), switching, by the PCEF, the UE from online charging to offline charging, and starting an offline timer when an online charging system (OCS) is unavailable, and restoring, by the PCEF, the UE from offline charging to online charging when the PCEF learns, before the offline timer expires, that the OCS becomes available. Hence, after a user is switched to offline charging, an online charging function can be recovered in a timely manner when the OCS becomes available. In this way, a user account overdraft risk possibly existing in an offline charging process is mitigated, and deactivation of the user can be avoided in the solutions, thereby improving user experience.

Abstract: A charging method, a network device, and a system, where the method includes performing, by a policy and charging enforcement function (PCEF), online charging for user equipment (UE), switching, by the PCEF, the UE from online charging to offline charging, and starting an offline timer when an online charging system (OCS) is unavailable, and restoring, by the PCEF, the UE from offline charging to online charging when the PCEF learns, before the offline timer expires, that the OCS becomes available. Hence, after a user is switched to offline charging, an online charging function can be recovered in a timely manner when the OCS becomes available. In this way, a user account overdraft risk possibly existing in an offline charging process is mitigated, and deactivation of the user can be avoided in the solutions, thereby improving user experience.