In a 5th-Generation (5G) cellular communication network, charging customers for data usage is performed by a network function referred to as a charging function (CHF). A session management function (SMF) of the network repeatedly sends update requests to reserve additional data for a data session. If the CHF is not available and the SMF does not receive a response to an update message, the SMF continues to assign data for the data session, even though it has not received authorization to do so from the CHF. When the CHF becomes available, the SMF sends a request to start a second data session to continue the data connection that was previously supported by the original data session. This request specifies the amount of data that was used in the original data session without being confirmed by the CHF, allowing the CHF to account for this data usage.