3GPP 23.501 v20.2.0 — the document's own text
5.8.2.20 SMF Pause of Charging
Taught in 13. Where the packets actually go (The 5G system architecture, in depth), 5. The connection, and what is promised on it (The 5G system architecture, overview).
The SMF Pause of Charging functionality is supported with the purpose that the charging and usage monitoring data in the core network more accurately reflects the downlink traffic actually sent to the (R)AN. When the amount of downlink data incoming at the UPF for a PDU Session that is in deactivated state goes above a pre-configured threshold, the pause of charging functionality ensures that data that dropped in the core network is not included in charging and usage monitoring records.
The procedures for SMF Pause of Charging are described in TS 23.502 [3].