12.053GPPSubscriber Related Call and Event DataTS
In order to provide the data required for the management activities outlined in the previous chapters (billing, accounting, statistics etc.), the NEF of the MSC and/or Location Registers shall be able to produce an event or call record for each of the following:
– Mobile originated call attempt;
– Mobile originated emergency call attempt;
– Mobile originated, call forwarding attempt;
– Mobile terminated call attempt;
– Roaming call attempt in a gateway MSC;
– Incoming call attempt in a gateway MSC;
– Outgoing call attempt from a gateway MSC;
– Transit call attempt;
– Terminating CAMEL interrogation call attempt;
– Supplementary service actions;
– HLR interrogation;
– Location updating (HLR & VLR);
– Short message service (point-to-point), mobile originated;
– Short message service (point-to-point), mobile terminated;
– Short message service (point-to-point), mobile originated interworking MSC;
– Short message service (point-to-point), mobile terminated gateway MSC;
– Common equipment usage.
The contents and purpose of each of these records are described in the following subclauses. A detailed formal description of the data defined in the present document is to be found in Annex A.
As not all of these records may be required for any given network, each record type shall be enabled/ disabled by means of the network management functions outlined in 126.96.36.199.
B.1.1 Use of supplementary services
The recording of supplementary service usage is controlled via the procedures outlined in subclause 188.8.131.52.3. These procedures permit the OS to specify the supplementary service actions (invocation, registration etc.) to be recorded.
In addition to specifying the actions to be recorded, the OS may also determine how these events are to be recorded. Non-call related events, such as the administration of supplementary services by the subscriber via the MMI of the MS, shall result in the production of supplementary service action records. Call related events (e.g. invocation of supplementary services) shall be recorded "in-line" in the appropriate call record and/ or in a separate SS-action record depending on the configuration specified by the OS.
Where the use of a supplementary service results in the production of further connections (e.g. call forwarding, multi-party service etc.) additional call records shall be produced to describe the relevant connections. The use of such services is described in more detail both in this subclause and in the example scenarios.
B.1.1.1 Use of call forwarding
When one of the call forwarding services is used, the NEF of the MSC that forwards the call, shall produce the call record for the forwarded part of the call. The call record produced is an MOC record as described in subclause B.2.3.
For further information concerning the recording of call forwarding services see the example scenarios in subclause B.4.6 and B.4.7.
B.1.1.2 Use of call hold and multi-party services
The use of the call hold service shall be recorded either in-line in the appropriate call record or in a separate supplementary service "invocation" record as described above. For the avoidance of doubt, the duration for which the call is held, i.e. is inactive, is not recorded.
The use of the multi-party service requires a minimum of 3 subscribers and the use of a conference circuit. For the purpose of the following description the subscriber invoking the service is referred to as the conference originator ("A") and the conference call is regarded as consisting of a number of individual "legs" between the organiser and the other parties ("B", "C", etc.) in the call.
Normal MOC and MTC call records shall be generated for each party and each leg of the call. In addition, if common equipment records are enabled, a common equipment record shall be produced for the conference originator in order to record the use of a conference bridge and to record the total duration of the conference connection.
Example: Subscriber "C" calls subscriber "A". Subscriber "A" places the call from "C" on hold and makes a second call to subscriber "B". Subscriber "A" then invokes the multi-party service in order to set-up a conference call with "B" and "C".
Assuming that the appropriate types of record are enabled, the following call records shall be produced:
– An MOC record for subscriber "C" and the "C"->"A" leg of the call;
– An MTC record for subscriber "A" and the "C"->"A" leg of the call;
– An MOC record for subscriber "A" and the "A"->"B" leg of the call;
– An SS-Action record for the invocation of the call hold service by subscriber "A";
– An MTC record for subscriber "B" and the "A"->"B" leg of the call;
– An SS-Action record for the invocation of the multi-party service by subscriber "A";
– A common equipment record for the use of the conference bridge by subscriber "A";
Each of the MOC/MTC records for the conference originator ("A") shall include the supplementary service code for the multi-party service.
Any subsequent action affecting only one leg of the connection shall be recorded either in a separate supplementary service action record or in-line in the appropriate call record. Any action affecting the conference as a whole e.g. the originator holding the conference shall be recorded either in a separate supplementary service action record or in the common equipment usage record.
For further information concerning the recording of multi-party services see the example scenario in subclause B.4.9.
B.1.2 Partial records
In order to increase the security of the recording process and to simplify post-processing, it may be desirable to generate a sequence of call records to describe a single connection or transaction.
In case of connections of extended duration, the loss of a single call record may result in an unacceptable loss of revenue. If the connection is, for example, recorded in a number of consecutive partial records generated at say hourly intervals, then the maximum loss of revenue is the equivalent of a one hour continuous connection.
Most modern billing systems employ some form of cumulative credit-limit checking based on the stream of input call records. If however, a call record is only produced at the end of the connection then a subscriber may avoid such credit checking by employing a connection for days, weeks or even months without a single call record being produced.
All of the records defined in the present document are of variable length and some at least are potentially unlimited in size (SET OF, SEQUENCE OF etc.). However, the storage capacity of the internal records within the NEF is normally subject to strict size limitations. Under such conditions a partial record may be required in order to circumvent internal resource limitations. For example, if an internal MOC record can only support the use of four supplementary service invocations then the use of a fifth may result in the generation of a partial record.
Alternatively, for those manufacturers whose systems are based on fixed length records, partial records may be employed instead of the various lists contained within the GSM 12.05 (the present document) definitions. In such cases a partial record will be produced each time one of the key fields alters during the connection.
Finally, in case of radio link failure and subsequent call re-establishment partial records shall be generated to record the duration of the call prior to the radio link failure and the subsequent duration of the call once the call has been re-established. For further details see subclause B.1.5.
To summarise, the following events may result in the generation of a partial record:
– expiry of the partial record timer;
– change of basic service during a connection;
– change of location (LAC or Cell Id.) during a connection;
– change of MS classmark during a connection;
– change of AoC Parameters during a call;
– change of Radio Channel Type (full/half rate) during a call;
– radio link failure and subsequent call re-establishment;
– change of HSCSD Parameters during a call;
– change of CAMEL destination (CAMEL controlled/initiated) during a call.
All partial records for the same connection shall contain the same call reference and shall be ordered via a running sequence number. The time stamps involved shall apply to the individual partial records rather than the connection as a whole i.e. the "end" time stamp (duration) of one record shall, in general, coincide with the "start" time stamp (answer time) of the next. Each time a new partial record is created the cause for termination of the previous field shall contain the value "partial record ". The cause for termination of the final partial record shall contain the true cause for termination of the connection.
It should be noted that the records produced in case of call re-establishment are not contiguous and that the value of the cause for term field in the record that is closed on radio link failure contains the value "partial record call re-establishment". For further details of these records see subclause B.2.18.
The partial records generated may repeat each of the non-varying fields contained in the original record. Alternatively, a form of reduced partial record may be generated which includes only those fields required to identify the original record together with the field(s) that actually change. An example of a reduced partial record for MOCs is provided in subclause B.2.18.
B.1.3 Use of packet data services
If packet data services are employed in conjunction with a Packet Switched Public Data Network (PSPDN) then an MOC/MTC call record may be produced in the originating/terminating MSC and a gateway record in the gateway/interworking MSC. If the packet volume is not available within the PLMN then this information may also be provided in the form of a call record from the PSPDN. In such cases the OS is responsible for the correlation of the various records describing the connection. The definition of such PSPDN call records is outside the scope of the present document.
B.1.4 Inter-msc handover
In the case of an inter-MSC handover the controlling MSC, as defined by GSM 03.09, remains in control of the connection and shall therefore, produce the call record. For the avoidance of doubt, it is not necessary to produce call or event records in the subsequent MSC(s).
B.1.5 Call re-establishment
In case of radio link failure as described in GSM 04.08 , the MS may attempt to re-establish the call using the procedures described in GSM 04.08 .
For the time period between the detection of the radio link failure by the mobile station and the successful re-establishment of the call, the advice of charge function in the MS is suspended as described in GSM 04.86. In order to minimise the difference in charges between the on-line calculations performed by the MS and the off-line processing on the basis of the call records, it is necessary to exclude the time taken for the re-establishment phase from the chargeable duration stored in the call records.
If the re-establishment attempt fails then an ordinary call record (MOC/MTC) shall be produced with the cause for termination value "stable call abnormal termination". The chargeable duration stored in this record covers the time period from "Answer" to the detection of the radio link failure by the MSC.
If, the attempt to re-establish the call succeeds then the current call record shall be closed with the cause for termination value "partial record call re-establishment" and a new partial record shall be opened for the re-established call. The chargeable duration stored in the original record is once again the time period from "answer" to detection of the radio link failure by the MSC. Both the "seizure" and "answer" times of the subsequent partial record correspond to the time at which the new traffic channel is allocated for the re-established call (see subclause B.3.16 for further details).
Further radio link failures during the re-established call may result in the generation of additional partial records as described above. All of the partial records belonging to the same connection are identified by the same call reference and a running sequence number as described in subclause
NOTE: As the MS and MSC may detect the radio link failure at different points in time, it is not possible to guarantee that the duration used for the AOC display corresponds to that recorded in the call records. The purpose of the above procedure is merely to minimise any discrepancies that may occur.
B.1.6 Restricted directory numbers
In addition to the information pertaining to the served mobile subscriber (IMSI, MSISDN, etc.), the call records defined in the present document also contain the directory numbers of other parties involved in the recorded connections or transactions. In order to comply with data protection legislation, it is necessary to distinguish between those numbers that may be passed on to third parties and those that needs to be handled confidentially. As a result, each of the number fields (e.g. calling/connected number) contains the presentation and screening information defined in both GSM 04.08  and ISUP signalling. If this information is supported by the network, then even restricted numbers may be included in the appropriate records and suppressed off-line by the administration or billing centre. If this information is not supported then the entire directory number shall be suppressed by the MSC/VLR.