7.3.1 Functional requirements of serving MSC

03.183GPPBasic call handlingRelease 1998TS

7.3.1.1 Process ICH_MSC

Sheet 1: the rules for converting the ISDN BC/LLC/HLC to a GSM bearer service or teleservice are specified in GSM 09.07 [24].

Sheet 1: the task "Store UUS information (if received)" is executed only if the VMSC supports UUS.

Sheet 1: the variables TCH allocated, ACM sent, Answer sent and Network connect sent are global data, accessible to the procedures Establish_Terminating_TCH_If_Required, Send_ACM_If_Required, Send_Answer_If_Required and Send_Network_Connect_If_Required.

Sheet 1: the variables UUS result sent, UUS1 implicit active, UUS1 explicit active, UUS2 active, UUS3 active and UUS CF interaction are specific to UUS. They are accessible to all UUS specific procedures.

Sheet 1: the procedure Process_Access_Request_MSC is specified in subclause 7.1.1.2.

Sheet 1, sheet 2: the suggested mapping from values of the Send Info For Incoming Call negative response information element to values of the ISUP release cause (see ITU‑T Recommendation Q.850 [28]) is shown in table 2. The mapping used is a matter for the network operator, depending on the telephony signalling system used.

Table 2: Suggested mapping of Send Info For Incoming Call (SIFIC) negative responses to ISUP release causes

SIFIC negative response

ISUP release cause number

ISUP release cause name

Absent subscriber

20

Subscriber absent

Busy subscriber

17

User busy

CUG reject (Called party SS interaction violation)

21

Call rejected

Forwarding violation

21

Call rejected

Impossible call completion

111

Protocol error, unspecified

No subscriber reply

19

No answer from user (user alerted)

System failure

111

Protocol error, unspecified

Unallocated roaming number

111

Protocol error, unspecified

Sheet 2: the processing in the branch starting with the input signal"Process Call Waiting" is specific to Call Wait. If the VMSC does not support CW this signal will not be received from the VLR.

Sheet 2, the procedure CD_Reject is specific to Call Deflection; it is specified in GSM 03.72 [7].

Sheet 2, sheet 4: the procedure CCBS_Set_Diagnostic_For_Release is specific to CCBS; it is specified in GSM 03.93 [19].

Sheet 2: the procedure UUS_ICH_Check_Support is specific to UUS; it is specified in GSM 03.87 [17].

Sheet 2, sheet 3, sheet 5: the procedure CCBS_Check_Last_Call is specific to CCBS; it is specified in GSM 03.93 [19].

Sheet 3: the procedure CAMEL_Check_ORLCF_VMSC is specific to CAMEL phase 2; it is specified in GSM 03.78 for CAMEL Phase 2 [9]. If the VMSC does not support CAMEL, processing continues from the “ORLCF” exit of the test “Result?”

Sheet 3: the procedure Handle_ORLCF_VMSC is specific to Support of Optimal Routeing. It is specified in TS 100 045 [10]. If the VMSC does not support Optimal Routeing, processing continues from the "Continue" exit of the test "Result?".

Sheet 3; the procedures CD_Failure and CD_Success are specific to Call Deflection; they are specified in GSM 03.72 [7].

Sheet 3: The task "set redirection information" includes the mapping of the MSISDN parameter received in the Send Info For Incoming Call ack message to the redirecting number of the IAM message and the setting of the presentation indicator of the redirecting number of the IAM message according to the value of the Redirecting presentation parameter received in the Send Info For Incoming Call ack message.

Sheet 3: it is an operator option whether to send an Address Complete message if the VLR returns forwarding information. If the VMSC sends an Address Complete message, it shall include the called party’s status field of the Backward call indicator set to "no indication".

Sheet 3, sheet 4: the procedure Send_ACM_If_Required is specified in subclause 7.2.1.3.

Sheet 3: the procedure Activate_CF_Process is specified in subclause 7.2.1.7.

Sheet 3: the procedure UUS_ICH_Set_Info_In_IAM is specific to UUS, it is specified in GSM 03.87 [17].

Sheet 3: the called party address sent in the IAM to the process MT_CF_MSC is the Forwarded-to number received in the Perform Call Forwarding ack.

Sheet 4: the procedure CCBS_MT_MSC_Check_Forwarding is specific to CCBS; it is specified in GSM 03.93 [19].

Sheet 4: the procedure Handle_COLP_Forwarding_Interaction is specified in subclause 7.2.1.6.

Sheet 4: the procedure Send_Answer_If_Required is specified in subclause 7.2.1.4.

Sheet 4: the procedure Send_Network_Connect_If_Required is specified in subclause 7.2.1.5.

Sheet 5: the procedure UUS_MSC_Check_UUS1_UUI is specific to UUS; it is specified in GSM 03.87 [17].

Sheet 6: after the VMSC has sent an IAM to the process MT_CF_MSC, it acts as a transparent relay for messages received from the GMSC and the process MT_CF_MSC. Any message other than Address Complete, Connect, Answer or Release causes no change of state in the process ICH_MSC.

7.3.1.2 Procedure Page_MS_MSC

Sheet 1: the test "MS connection exists" takes the "Yes" exit if there is a radio connection established between the MS and the network.

Sheet 1: for an SMS or SS page, the test "Call still exists" takes the "Yes" exit if the SMS or SS transaction which led to the page still exists.

Sheet 1: the test "SMS or SS page" is not required for the handling of circuit-switched calls, because the VLR will always use a page type of "circuit-switched call", but the more generalised procedure Page_MS_MSC is equally applicable to paging for SMS delivery or network-initiated SS procedures.

Sheet 1: the test "MS busy" takes the "Yes" exit if the MS is engaged on a circuit-switched call.

Sheet 1: the test "Call in set-up" takes the "Yes" exit if the call on which the MS is engaged has not reached the established phase (called party answer).

Sheet 1: the test Call waiting" takes the "Yes" exit if a waiting call has been offered to the subscriber but the outcome of offering the call has not been determined.

Sheet 1: the negative response Busy Subscriber (More calls possible) includes the basic service which applies for the established call.

Sheet 2: the signal input "MS connection established" indicates that the MS has responded to paging, or sent a CM service request for anything other than a circuit-switched call, or completed the location registration procedure.

7.3.1.3 Procedure Search_For_MS_MSC

Sheet 1: the test "MS connection exists" takes the "Yes" exit if there is a radio connection established between the MS and the network.

Sheet 1: for an SMS or SS page, the test "Call still exists" takes the "Yes" exit if the SMS or SS transaction which led to the page still exists.

Sheet 1: the test "SMS or SS page" is not required for the handling of circuit-switched calls, because the VLR will always use a page type of "circuit-switched call", but the more generalised procedure Search_For_MS_MSC is equally applicable to paging for SMS delivery or network-initiated SS procedures.

Sheet 1: the test "MS busy" takes the "Yes" exit if the MS is engaged on a circuit-switched call.

Sheet 1: the test "Call in set-up" takes the "Yes" exit if the call on which the MS is engaged has not reached the established phase (called party answer).

Sheet 1: the test "Call waiting" takes the "Yes" exit if a waiting call has been offered to the subscriber but the outcome of offering the call has not been determined.

Sheet 1: the negative response Busy Subscriber (More calls possible) includes the basic service which applies for the established call.

Sheet 2: the signal input "MS connection established" indicates that the MS has responded to paging, or sent a CM service request for anything other than a circuit-switched call, or completed the location registration procedure.

7.3.1.4 Procedure Complete_Call_In_MSC

Sheet 1: the procedure Set_CLIP_Info_MSC is specific to CLIP.

Sheet 1: the VMSC and the MS may negotiate the bearer capability to be used for the call by the exchange of information in the Setup and Call Confirmed messages.

Sheet 1: the procedure UUS_ICH_UUS1_Implicit_Active is specific to UUS, it is specified in GSM 03.87 [17].

Sheet 1: the procedure CCBS_Report_Not_Idle is specific to CCBS; it is specified in GSM 03.93 [19].

Sheet 1, sheet 2, sheet 4: the procedure CCBS_ICH_MSC_Report_Failure is specific to CCBS; it is specified in GSM 03.93 [19].

Sheet 2: the procedure CCBS_ICH_MSC_Report_Success is specific to CCBS; it is specified in GSM 03.93 [19].

Sheet 2, sheet 5: the processing in the branch starting with the input "CD Request" is specific to Call Deflection; if the VMSC does not support Call Deflection the input is discarded.

Sheet 2, sheet 5: the procedure Handling_CD_MSC is specific to Call Deflection; it is specified in GSM 03.72 [7].

Sheet 2, sheet 3: the procedure UUS_ICH_Check_Support is specific to UUS, it is specified in GSM 03.87 [17]. If the VMSC does not support UUS, the execution continues from the “Yes” exit of the test “Result=Pass?”.

Sheet 2: the task "UTU2Cnt:=0" is executed only if the VMSC supports UUS.

Sheet 2: the procedure Send_ACM_If_Required is specified in subclause 7.2.1.3.

Sheet 2, sheet 3: the procedure Handle_AoC_MT_MSC is specific to AoC. If the VMSC does not support AoC, processing continues from the "Yes" exit of the test "Result=Pass?".

Sheet 2, sheet 3: the procedure Set_COL_Presentation_Indicator_MSC is specific to COLP.

Sheet 2: the procedure Send_Network_Connect_If_Required is specified in subclause 7.2.1.5.

Sheet 3, sheet 5: the procedure UUS_ICH_Check_Forwarding is specific to UUS, it is specified in GSM 03.87 [17]. If the VMSC does not support UUS, the execution continues from the "Yes" exit of the test "Result=Pass?".

Sheet 3: the procedure Send_Answer_If_Required is specified in subclause 7.2.1.4.

Sheet 4, sheet 5: the procedure UUS_MSC_Check_UUS1_UUI is specific to UUS; it is specified in GSM 03.87 [17].

Sheet 5: the procedures UUS_MSC_Check_UUS2_UUI_to MS and UUS_MSC_Check_UUS2_UUI_to NW are specific to UUS, they are specified in GSM 03.87 [17].

Sheet 5: the procedure CD_UUS_Interaction is specific to Call Deflection; it is specified in GSM 03. 72 [7].

7.3.1.5 Procedure Process_Call_Waiting_MSC

Sheet 1: the procedure Set_CLIP_Info_MSC is specific to CLIP.

Sheet 1, sheet 2: the VMSC and the MS may negotiate the bearer capability to be used for the call by the exchange of information in the Setup and Call Confirmed messages.

Sheet 1: the procedure UUS_ICH_UUS1_Implicit_Active is specific to UUS; it is specified in GSM 03.87 [17].

Sheet 1: the procedure CCBS_Report_Not_Idle is specific to CCBS; it is specified in GSM 03.93 [19].

Sheet 2, sheet 3, sheet 4: the procedure UUS_ICH_Check_Support is specific to UUS; it is specified in GSM 03.87 [17]. If the VMSC does not support UUS, the execution continues from the "Yes" exit of the test "Result=Pass?" where the test follows the procedure call.

Sheet 2: the procedure CCBS_ICH_MSC_Report_Success is specific to CCBS; it is specified in GSM 03.93 [19].

Sheet 2, sheet 5: the processing in the branch starting with the input "CD Request" is specific to Call Deflection; if the VMSC does not support Call Deflection the input is discarded.

Sheet 2, sheet 5: the procedure Handling_CD_MSC is specific to Call Deflection; it is specified in GSM 03.72 [7].

Sheet 2: the task "UTU2Cnt:=0" is executed only if the VMSC supports UUS.

Sheet 2, sheet 5: the procedure CCBS_ICH_MSC_Report_Failure is specific to CCBS; it is specified in GSM 03.93 [19].

Sheet 2: the Call Confirmed message indicates "busy" for the successful case.

Sheet 2: the procedure Send_ACM_If_Required is specified in subclause 7.2.1.3.

Sheet 2, sheet 4: the Release transaction (reject) message covers all unsuccessful cases not otherwise indicated.

Sheet 3: the procedure Handle_AoC_MT_MSC is specific to AoC. If the VMSC does not support AoC, processing continues from the "Yes" exit of the test "Result=Pass?".

Sheet 3: the procedure Set_COL_Presentation_Indicator_MSC is specific to COLP.

Sheet 3: the procedure Send_Answer_If_Required is specified in subclause 7.2.1.4.

Sheet 4, sheet 5: the procedure UUS_ICH_Check_Forwarding is specific to UUS; it is specified in GSM 03.87 [17]. If the VMSC does not support UUS, the execution continues from the "Yes" exit of the test "Result=Pass?".

Sheet 5: the procedures UUS_MSC_Check_UUS1_UUI, UUS_MSC_Check_UUS2_UUI_to_MS and UUS_MSC_Check_UUS2_UUI_to_NW are specific to UUS; they are specified in GSM 03.87 [17].

Sheet 5: the procedure CD_UUS_Interaction is specific to Call Deflection; it is specified in GSM 03. 72 [7].

7.3.1.6 Procedure Set_CLIP_Info_MSC

The originating exchange may release the call or the MS may terminate the transaction with the network by sending a Release transaction message while a response is awaited from the process CLIP_MAF002. The message is saved for processing after return from the procedure.

7.3.1.7 Procedure Derive_GSM_BC_MSC

7.3.1.8 Procedure Establish_Terminating_TCH_If_Required

7.3.1.9 Procedure Handle_AoC_MT_MSC

7.3.1.10 Procedure Set_COL_Presentation_Indicator_MSC

The originating exchange may release the call or the MS may terminate the transaction with the network by sending a Release transaction message while a response is awaited from the process COLP_MAF041. The message is saved for processing after return from the procedure.

Figure 59a: Process ICH_MSC (sheet 1)

Figure 59b: Process ICH_MSC (sheet 2)

Figure 59c: Process ICH_MSC (sheet 3)

Figure 59d: Process ICH_MSC (sheet 4)

Figure 59e: Process ICH_MSC (sheet 5)

Figure 59f: Process ICH_MSC (sheet 6)

Figure 60a: Procedure Page_MS_MSC (sheet 1)

Figure 60b: Procedure Page_MS_MSC (sheet 2)

Figure 61a: Procedure Search_For_MS_MSC (sheet 1)

Figure 61b: Procedure Search_For_MS_MSC (sheet 2)

Figure 62a: Procedure Complete_Call_In_MSC (sheet 1)

Figure 62b: Procedure Complete_Call_In_MSC (sheet 2)

Figure 62c: Procedure Complete_Call_In_MSC (sheet 3)

Figure 62d: Procedure Complete_Call_In_MSC (sheet 4)

Figure 62e: Procedure Complete_Call_In_MSC (sheet 5)

Figure 63a: Procedure Process_Call_Waiting_MSC (sheet 1)

Figure 63b: Procedure Process_Call_Waiting_MSC (sheet 2)

Figure 63c: Procedure Process_Call_Waiting_MSC(sheet 3)

Figure 63d: Procedure Process_Call_Waiting_MSC(sheet 4)

Figure 63e: Procedure Process_Call_Waiting_MSC(sheet 5)

Figure 64: Procedure Set_CLIP_Info_MSC

Figure 65: Derive_GSM_BC_MSC

Figure 66: Procedure Establish_Terminating_TCH_If_Required

Figure 67: Procedure Handle_AoC_MT_MSC

Figure 68: Procedure Set_COL_Presentation_Indicator MSC