8 Advice Of Charge Services

This chapter describes how to use the AG ISDN Advice of Charge (AOC) supplementary services, available within the ETS 300 variant.

The Advice of Charge services provide users with a way of tracking the costs of a specific call, in real time. Three AOC services are available, each of which causes AOC information to be returned at a different point in the call:

Invocation of the Advice of Charge service is performed by the originating node, on a call-by-call basis. Once AOC is invoked, the originating node receives charging information using supplementary service data structures.

Alternatively, as a subscription option, the interface can be configured to provide Advice of Charge on all calls. In this case, the originating user side does not need to invoke the service. However, the NAI must be configured locally with the AOC subscription options (see Section 8.4).

Note: The basic call signaling over the network is affected by AOC services. In call clearing cases, the call clearing procedure will be delayed until AOC signaling is completed.

Note: Advice of Charge services are not available under Q.SIG.

If Advice of Charge services are not provided using a subscription service, they must be invoked to be used. Invocation of the services at the originating node is accomplished on a per-call basis. To invoke AOC services, an ACU_CONN_RQ primitive is sent to the stack, containing an acu_ss_aoc_request_invoke extended data structure. The service header to this structure must contain:

The following is a listing of the acu_ss_aoc_request_invoke extended data structure:

struct acu_ss_aoc_request_invoke  
{  
  struct acu_ext_hdr ext_hdr; /* Extension header 	*/  
  struct acu_ss_hdr  ss_hdr;  /* Supp. services header 	*/  
  uchar              aoc_s;   /* Request AOC-S services (ON/OFF)	*/  
  uchar              aoc_d;   /* Request AOC-D services (ON/OFF)	*/  
  uchar              aoc_e;   /* Request AOC-E services (ON/OFF)	*/  
  pad5  
};

The following is a list of the fields in this structure (other than the header fields). All fields are mandatory.

Any combination of one or more AOC services is allowed in the request message.

If AOC services are successfully invoked, an acu_ss_aoc_request_ret_result extended data structure is returned in an ACU indication or confirmation message. The service header to this structure contains:

The following is a listing of the acu_ss_aoc_request_ret_result extended data structure:

struct acu_ss_aoc_request_ret_result  
{  
  struct acu_ext_hdr ext_hdr; /* Extension header 	*/  
  struct acu_ss_hdr  ss_hdr;  /* Supp. services header 	*/  
  uchar              aoc_s;   /* AOC-S services active (ON/OFF)	*/  
  uchar              aoc_d;   /* AOC-D services active (ON/OFF)	*/  
  uchar              aoc_e;   /* AOC-E services active (ON/OFF)	*/  
  pad5  
};

The following is a list of the fields in this structure (other than the header fields). All fields are mandatory.

The application may receive one acu_ss_aoc_request_ret_result message indicating the activation of all AOC services, or one for each service. If the application receives a message indicating that not all requested services are activated, this does not necessarily imply an error. Instead, it may mean that results are not yet available for the other services. Subsequent messages contain the activation results for these services.

If AOC services are not successfully invoked, an acu_ss_aoc_request_ret_error extended data structure is returned in an ACU indication or confirmation message. The service header to this structure contains:

The following is a listing of the acu_ss_aoc_request_ret_error extended data structure:

struct acu_ss_aoc_request_ret_error  
{  
  struct acu_ext_hdr ext_hdr; /* Extension header 	*/  
  struct acu_ss_hdr  ss_hdr;  /* Supp. services header 	*/  
  ushort             cause;   /* From ACU_SS_AOC_ERR.. constants 	*/  
  uchar              aoc_s;   /* Error applies to AOC-S service (ON/OFF)	*/  
  uchar              aoc_d;   /* Error applies to AOC-D service (ON/OFF)	*/  
  uchar              aoc_e;   /* Error applies to AOC-E service (ON/OFF)	*/  
  pad3  
};

The following is a list of the fields in this structure (other than the header fields).

Figure 42: AOC Request Procedure During Call Establishment

When Advice of Charge data is available, the application receives an ACU indication or confirmation message, containing an acu_ss_aoc_inform_invoke extended data structure with:

The following is a listing of the acu_ss_aoc_inform_invoke extended data structure:

struct acu_ss_aoc_inform_invoke  
{  
  struct acu_ext_hdr ext_hdr; /* Extension header 	*/  
  struct acu_ss_hdr  ss_hdr;  /* Supp. services header 	*/  
  uchar  aoc_type;            /* From ACU_SS_AOC_TYPE... constants 	*/  
  pad7  
  union  
  {  
    tAcuSSAocSInform aoc_s;   /* aoc_type==AOC_SS_TYPE_AOC_S_INFORM	*/  
    tAcuSSAocDInform aoc_d;   /* aoc_type==AOC_SS_TYPE_AOC_D_INFORM	*/  
    tAcuSSAocEInform aoc_e;   /* aoc_type==AOC_SS_TYPE_AOC_E_INFORM	*/  
  } aoc_data;  
};

The following is a list of the fields in this structure (other than the header fields), and when they are used.

Charging information is delivered to the application using the extended service data area of an ACU primitive during the active part of the call.

If AOC-S is active, the aoc_type field in acu_ss_aoc_inform_invoke is set to ACU_SS_AOC_TYPE_AOC_S_INFORM. The tAcuSSAocSInform data structure and substructures are used to carry Advice of Charge data.

The following is a listing of the tAcuSSAocSInform structure.

typedef struct tAcuSSAocSInform  
{  
  uchar type_of_info;           /* From ACU_SS_AOC_TYPE_OF_INFO_ constants	*/  
  uchar charged_item;           /* Bitmap of charged item constants	*/  
  uchar charging_rate;          /* One of charging rate constants 	*/  
  pad5  
  union   
  {  
    tAcuSSAocDuration duration; /* charging_rate=CHARGING_RATE_DURATION	*/  
    tAcuSSAocSpecific specific; /* charging_rate=CHARGING_RATE_SPECIFIC	*/  
    tAcuSSAocVolume   volume;   /* charging_rate=CHARGING_RATE_VOLUME	*/  
  }rate;  
};

The following is a list of the fields in this structure (other than the header fields). Fields marked "M" in the "IN"column are mandatory in ACU indication or confirmation messages. Fields marked "O" are optional.

If there is charging rate information returned, the type_of_info field in the tAcuSSAocSInform structure contains CHARGE_RATE. Otherwise, the field contains NOT_AVAILABLE.

If type_of_info in tAcuSSAocSInform contains CHARGE_RATE, the charged_item field in the structure contains the charged item. The following are valid values for this field:

Note: Network providers will only use those charged items which are appropriate to that service provider's charging mechanism. Thus, in some networks, users may or may not receive some of these items or combinations of items. Different networks may give information about the same call in different ways.

Different charging rates are associated with each of the charged item types. If a charged item is not included, the default value is interpreted as "free of charge."

The charging rate is specified in the charging_rate field in the tAcuSSAocSInform structure. Depending upon its setting, one of the following data structures contains additional data:

The following table lists the charging_rate field setting and associated data structure for each charging rate type:

The following is a listing of the tAcuSSAocDuration structure.

typedef struct tAcuSSAocDuration  
{  
  struct op_byte_field multiplier;        /* Applies to currency amount 	*/  
  struct op_long_field currency_amount;   /* No. of currency units charged	*/  
  struct op_long_field time;              /* Number of time units charged	*/  
  struct op_long_field granularity;       /* Integer or not included 	*/  
  struct op_byte_field time_scale;        /* Applies to time 	*/  
  struct op_byte_field granularity_scale; /* Applies to granularity	*/  
  struct op_byte_field currency_id_size;  /* 0 if currency id not included	*/  
  uchar  currency_id[MAX_CURRENCY_SIZE];  /* Currency ID 	*/  
  uchar  type_of_charging;                /* From SS_AOC_S_TYPE_OF_CHARGE	*/  
  pad3                                    /* constants	*/  
};

The following is a list of the fields in this structure. Fields marked "M" in the "IN"column are mandatory in ACU indication or confirmation messages. Fields marked "O" are optional.

The following is a listing of the tAcuSSAocSpecific structure.

typedef struct tAcuSSAocSpecific  
{  
  struct op_byte_field multiplier;       /* From ACU_SS_AOC_MULTIPLIER_	*/  
                                         /* constants	*/  
  struct op_long_field currency_amount;  /* No. of currency units charged	*/  
  struct op_byte_field charge_code;      /* 10	*/  
  struct op_byte_field currency_id_size; /* No. of bytes from currency_id	*/  
  uchar  currency_id[MAX_CURRENCY_SIZE]; /* Currency ID string	*/  
  uchar  rate_type;                      /* From ACU_SS_AOC_RATE_TYPE_	*/  
  pad3                                   /* constants	*/  
};

The following is a list of the fields in this structure. Fields marked "M" in the "IN"column are mandatory in ACU indication or confirmation messages. Fields marked "O" are optional.

The following is a listing of the tAcuSSAocVolume structure.

typedef struct tAcuSSAocVolume  
{  
  struct op_long_field currency_amount;    /* No of currency units charged	*/  
  struct op_byte_field currency_id_size;   /* No of bytes from currency_id	*/  
  struct op_byte_field multiplier;         /* From ACU_SS_AOC_MULTIPLIER_	*/  
                                           /* constants	*/  
  uchar    currency_id[MAX_CURRENCY_SIZE]; /* Currency ID string 	*/  
  uchar    volume_type;                    /* From ACU_SS_AOC_VOLUME_TYPE_	*/  
  pad3                                     /* constants	*/  
};

The following is a list of the fields in this structure. Fields marked "M" in the "IN"column are mandatory in ACU indication or confirmation messages. Fields marked "O" are optional.

If AOC-D is active, the aoc_type field in the acu_ss_aoc_inform_invoke structure is set to ACU_SS_AOC_TYPE_AOC_D_INFORM. The tAcuSSAocDInform data structure and substructures are used to carry Advice of Charge data.

The following is a listing of the tAcuSSAocDInform structure.

typedef struct tAcuSSAocDInform  
{  
  struct op_byte_field currency_id_size; /* Used only if type_of_charging	*/  
                                         /* is CURRENCY_UNITS	*/  
  struct op_long_field currency_amount;  /* Used only if type_of_charging	*/  
                                         /* is CURRENCY_UNITS	*/  
  struct op_byte_field multiplier;       /* Used only if type_of_charging	*/  
                                         /* is CURRENCY_UNITS	*/  
  struct op_byte_field billing_id;       /* From ACU_SS_AOC_BILLING_ID	*/  
                                         /* constants	*/  
  struct acu_ss_association charge_association; /* Returns ID of charge	*/  
                                         /* for AOC-E after call clearing 	*/  
  tRecordedUnits       recorded_units;   /* Used only if type_of_charging	*/  
                                         /* is CHARGING_UNITS	*/  
  uchar currency_id[MAX_CURRENCY_SIZE];  /* Used only if type_of_charging	*/  
                                         /* is CURRENCY_UNITS	*/  
  uchar type_of_charging;                /* From SS_AOC_TYPE_OF_CHARGE...	*/  
                                         /* constants	*/  
  uchar recorded_charges;                /* From SS_AOC_RECORDED_CHARGES	*/  
                                         /* constants	*/  
  uchar completed;                       /* Set to OFF if additional	*/  
                                         /* recorded units are queued 	*/  
  pad1                                   /* in a subsequent message 	*/  
};

The following is a list of the fields in this structure (other than the header fields).

If AOC-E is active, the aoc_type field in the acu_ss_aoc_inform_invoke structure is set to ACU_SS_AOC_TYPE_AOC_E_INFORM. The tAcuSSAocEInform data structure and substructures are used to carry Advice of Charge data.

The following is a listing of the tAcuSSAocEInform structure.

typedef struct tAcuSSAocEInform  
{  
  struct op_byte_field currency_id_size;/* Used only if type_of_charging	*/  
                                        /* is CURRENCY_UNITS	*/  
  struct op_long_field currency_amount; /* Used only if type_of_charging	*/  
                                        /* is CURRENCY_UNITS	*/  
  struct op_byte_field multiplier;      /* Used only if type_of_charging	*/  
                                        /* is CURRENCY_UNITS	*/  
  struct op_byte_field billing_id;      /* From ACU_SS_AOC_BILLING_ID	*/  
                                        /* constants	*/  
  struct acu_ss_association charge_association; /* Returns ID of charge	*/  
                                        /* for AOC-E after call clearing 	*/  
  tRecordedUnits       recorded_units;  /* Used only if type_of_charging	*/  
                                        /* is CHARGING_UNITS	*/  
  uchar currency_id[MAX_CURRENCY_SIZE]; /* Used only if type_of_charging	*/  
                                        /* is CURRENCY_UNITS	*/  
  uchar type_of_charging;               /* From SS_AOC_TYPE_OF_CHARGE...	*/  
                                        /* constants	*/  
  uchar recorded_charges;               /* From SS_AOC_RECORDED_CHARGES	*/  
                                        /* constants	*/  
  uchar completed;                      /* Set to OFF if additional	*/  
                                        /* recorded units are queued 	*/  
  pad1                                  /* in a subsequent message 	*/  
};

The following is a list of the fields in this structure (other than the header fields).

Figure 43: Transfer of Charging Information During the Active State of a Call

Figure 44: Transfer of Charging Information During the Call Clearing Phase, Clearing Initiated by the Calling User

Figure 45: Transfer of Charging Information During the Call Clearing Phase, Clearing Initiated by the Called User

The Advice of Charge service interacts with the Explicit Call Transfer service. This section describes how the services interact.

If AOC-S is active at the time the served user invokes the Explicit Call Transfer service, then AOC-S is stopped, and the application may get advice of charge prior to the clearing of the call.

If AOC-D is active at the time the served user invokes the Explicit Call Transfer service, then the application receives advice of charge information prior to the clearing of the call, and the service is stopped.

If the served user continues to be charged for a call after the call is transferred elsewhere, the served user can associate an identifier with the call, so AOC-E information for the call can be returned to the served user even though the served user is no longer involved in the call. (See Figure 46.)

The identifier is specified in the charge_association field in the Explicit Call Transfer or data structure. When AOC-E information is returned at the end of the call, the information is presented to the application using the management SAPI (ACU_MGMT_SAPI) in the AOC_INFORM structure, using a dummy connection id. The charge_association field in the AcuSSAocEInform data structure is filled in, enabling the application to associate the charging information to the specific invocation of the service.

If an identifier is not specified with the call, no AOC information is returned.

If AOC-E is activated for a call, and the Explicit Call Transfer service is called without a charge identifier included, then the AOC-E service is stopped, and the application receives AOC-E information for the portion of the call prior to the transfer.

Figure 46: AOC and Call Transfer

The Advice of Charge service interacts with the Call Deflection service. This section describes how the services interact.

AOC-S and AOC-D services are not applicable to the user performing the deflection.

If the served user continues to be charged for a call after the call is deflected elsewhere, the served user can associate an identifier with the call, so AOC-E information for the call can be returned to the served user even though the served user is no longer involved in the call.

The identifier is specified in the charge_association field in the Call Deflection data structure. When AOC-E information is returned at the end of the call, the information is presented to the application using the management SAPI (ACU_MGMT_SAPI) in the AOC_INFORM structure, using a dummy connection id. The charge_association field in the AcuSSAocEInform data structure is filled in, enabling the application to associate the charging information to the specific invocation of the service.

If AOC-E is activated for a call, and the Call Deflection service is called without a charge identifier included, then the AOC-E service is stopped, and the application receives AOC-E information for the portion of the call prior to the deflection.

If you have subscribed to Advice of Charge services, to use the services in this manner you must specify which AOC service you have subscribed to when you start the ISDN stack on an NAI. You can specify this information in the ISDN_PROTOCOL_PARMS_Q931CC structure referenced in the initial call to isdnStartProtocol. The fields to fill are as follows:

For more information, see your AG ISDN Messaging API Developer's Reference Manual.