A.1 Call scenarios with AoC Information provided at the beginning and/or during and/or at the end of the call

32.2803GPPAdvice of Charge (AoC) serviceCharging managementRelease 17Telecommunication managementTS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

A.1.1 Outgoing call with Tariff provided by the charging domain at the start of the call

Actors:	Alan and Brendan are telecoms subscribers. Alan is an IMS subscriber with AoC service(s).
Description:	Tariff information is provided to Alan at the start of the call.
Preconditions:	AoC-related subscription status and user profile for Alan are stored in the HSS.
Post conditions:	Alan is ready to proceed with his call after receiving the tariff information applicable to the call.
Normal Flow:	Alan initiates an IMS session to call Brendan The tariff for the call is sent to Alan at the beginning of the call Alan receives the AoC Information on his UE
Alternative Flows:
Assumptions:	The charging domain (online or offline) has the tariff for this call.
Notes and Issues:

A.1.2 Outgoing call with Tariff provided by a remote network (PSTN or IMS) or a 3^rd party service provider (AS) at the start of the call

Actors:	Alan and Brendan are telecoms subscribers. Alan is an IMS subscriber with AoC service(s).
Description:	Tariff information is provided to Alan at the start of the call.
Preconditions:	AoC-related subscription status and user profile for Alan are stored in the HSS.
Post conditions:	Alan is ready to proceed with his call after receiving the tariff information applicable (from the remote network or 3^rd party service provider ) to the call.
Normal Flow:	Alan initiates an IMS session to call Brendan The tariff for the call is sent to Alan at the beginning of the call Alan receives the AoC Information on his UE
Alternative Flows:
Assumptions:	The tariff for this call is not available in the charging domain (online or offline). Tariff information can be transferred in real-time from the remote network or 3^rd party service provider.
Notes and Issues:

A.1.3 Outgoing call with Tariff provided by the charging domain in addition to an add-on charge received from the remote network (PSTN or IMS) or from a 3^rd party service provider (AS)

Actors:	Alan and Brendan are telecoms subscribers. Alan is an IMS subscriber with AoC service(s).
Description:	Tariff information incorporating an add-on charge from an external source is provided to Alan at the start/during of the call.
Preconditions:	AoC-related subscription status and user profile for Alan are stored in the HSS.
Post conditions:	Alan is ready to proceed/continue with his call after receiving the tariff information applicable to the call.
Normal Flow:	Alan initiates an IMS session to call Brendan The tariff for the call is sent to Alan at the beginning of the call Alan receives the AoC Information on his UE including the add-on charge from the remote network (PSTN or IMS) or from a 3^rd party service provider.
Alternative Flows:	An IMS session between Alan and Brendan is proceeding The tariff for the call is sent to Alan during the call Alan receives the AoC Information on his UE including the add-on charge from the remote network (PSTN or IMS) or from a 3^rd party service provider.
Assumptions:	The charging domain (online or offline) has the tariff for this call. Add-on charges can be transferred in real-time for the remote network or 3^rd party service provider.
Notes and Issues:

A.1.4 Outgoing call with Tariff change provided by the charging domain during an on-going call

Actors:	Alan and Brendan are telecoms subscribers. Alan is an IMS subscriber with AoC service(s).
Description:	Tariff information is provided to Alan when there is a tariff switch during a call.
Preconditions:	AoC-related subscription status and user profile for Alan are stored in the HSS. There is an on-going call between Alan and Brendan.
Post conditions:	Alan is ready to continue his call with Brendan after receiving the updated tariff information that is now applicable to the call.
Normal Flow:	Alan initiates an IMS session to call Brendan. A tariff switch relevant to this call occurs. The new tariff for the call is sent to Alan. Alan receives the updated tariff information on his UE.
Alternative Flows:
Assumptions:	The charging domain (online or offline) has the tariff for this call.
Notes and Issues:

A.1.5 Outgoing call with regular Cost updates provided by the charging domain during an on-going call

Actors:	Alan and Brendan are telecoms subscribers. Alan is an IMS subscriber with AoC service(s).
Description:	Cost information is provided to Alan at regulated periods during a call.
Preconditions:	AoC-related subscription status and user profile for Alan are stored in the HSS. There is an on-going call between Alan and Brendan.
Post conditions:	Alan is ready to continue his call with Brendan after receiving the accumulated cost information that is now applicable to the on-going call.
Normal Flow:	Alan initiates an IMS session to call Brendan. The duration of the call exceeds a predefined marker. The accumulated cost for the call to date is sent to Alan. Alan receives the updated cost information on his UE.
Alternative Flows:
Assumptions:	The charging domain can determine the accumulated costs for this call in real-time.
Notes and Issues:

A.1.6 Outgoing call with Cost summary provided at the end of the call

Actors:	Alan and Brendan are telecoms subscribers. Alan is an IMS subscriber with AoC service(s).
Description:	Cost information is provided to Alan at the end of a call.
Preconditions:	AoC-related subscription status and user profile for Alan are stored in the HSS. There is an on-going call between Alan and Brendan.
Post conditions:	Alan has completed his call with Brendan and receives the accumulated cost information that is now applicable to the preceding call.
Normal Flow:	Alan terminates an IMS session for a call to Brendan. The accumulated costs for the call are sent to Alan. Alan receives the cost information on his UE.
Alternative Flows:
Assumptions:	The charging domain can determine the accumulated costs for this call in real-time.
Notes and Issues:

A.1.7 Incoming call with Tariff provided by the charging domain at the start of the call

Actors:	Alan and Brendan are telecoms subscribers. Brendan is an IMS subscriber with AoC service(s).
Description:	Tariff information is provided to Brendan at the start of the call.
Preconditions:	AoC-related subscription status and user profile for Brendan are stored in the HSS.
Post conditions:	Brendan is ready to proceed with his call from Alan after receiving the tariff information applicable to the call.
Normal Flow:	Alan initiates an IMS session to call Brendan The tariff for the call is sent to Brendan at the beginning of the call Brendan receives the AoC Information on his UE
Alternative Flows:
Assumptions:	The charging domain (online or offline) has the tariff for this call. There are business rules that determine that Brendan is the charged party for this call.
Notes and Issues:

Annex B (informative):
Message flow for basic IMS session establishment and interaction with online charging

This annex describes the basic IMS session establishment for a user registered for AoC service(s) and the interaction with online charging when an AS or the IMS GWF handles Debit Units operation.

Figure B.1 shows a basic IMS session establishment when an AS or the IMS GWF controls online charging.

Figure B.1: Basic IMS session establishment for a user registered to AoC service(s)
(online case controlled by AS / IMS GWF)

– Step 1: An initial SIP INVITE message is received in the S-CSCF.

– Step 2: The S-CSCF forwards this request to the AoC function.

– Step 3: The AoC function needs to request the tariff and or cost for this session. An AoC Enquiry is sent to the OCS in a Debit Units Request message.

– Step 4: The OCS sends back to the AoC function the information requested (tariff/cost).

– Step 5: The AoC Information is included by the ACF in a SIP 183 response.

– Step 6: UE acknowledgement of the 183 response is received at the ACF.

– Step 7: The SIP INVITE is forwarded to the S-CSCF.

– Step 8: The S-CSCF forwards the SIP INVITE message to the IMS GWF/AS to perform the online charging.

– Step 9: The IMS GWF/AS reserves a credit for the session. A Debit Units Request message is sent to the OCS. This Debit Units Request message is composed of a unit reservation request.

– Step 10: The OCS sends back to the IMS-GWF/AS a credit for the session.

– Step 11: The INVITE message is forwarded by the IMS GWF/AS to the S-CSCF.

– Step 12: The S-CSCF forwards the SIP INVITE message to the terminating party.

The service logic (AS/IMS GWF) and the AoC function may be unified. Thus, instead of sending two Debit Units Request messages (Debit Units Request [RSU] and Debit Units Request[AoC Enquiry] messages) towards the OCS, a grouped Debit Units Request message may be sent for performance reasons.

Figure B.2: Basic IMS session establishment for a user registered to AoC service(s)
(online case controlled by unified (IMS GWF/AS) and ACF)

– Step 1: An initial SIP INVITE message is received in the S-CSCF.

– Step 2: The S-CSCF forwards this request to the AoC function.

– Step 3: The unified (IMS GWF or AS) and ACF generates a Debit Units Request message containing both a credit request and an AoC enquiry.

– Step 4: The OCS sends back to the unified (IMS GWF or AS) and ACF a response to the credit authorization and AoC enquiry.

– Step 5: The AoC Information is included by the unified (IMS GWF or AS) and ACF in a SIP 183 response.

– Step 6: UE acknowledgement of the 183 response is received at the unified (IMS GWF or AS) and ACF.

– Step 7: The SIP INVITE is forwarded to the S-CSCF.

– Step 8: The S-CSCF forwards the SIP INVITE message to the terminating party.

Annex C (informative):
AoC Information mapping