Shutting down primary charge collection function (CCF) without creating incomplete sets of charging data records (DR) in primary and secondary CCFs

A shutdown notice may indicate that a primary CCF system is expected to shutdown soon. This notice may be received by a CTF system after the CTF system delivers an ACR Start message to the primary CCF system, but before it delivers an ACR Stop message relating to the same chargeable session to the primary CCF system. In response to this shutdown notice, the CTF system may be configured to deliver an ACR Stop message relating to the same chargeable session to the primary CCF system before the primary CCF system shuts down. Also in response to this shutdown notice, the CTF system may be configured to deliver an additional ACR Start message and an ACR Stop message relating to the same chargeable session to a secondary CCF system.