Service Switching
3.9 SSF Function Blocks
3.9.1 SSFDCF
SSFDCF is the main data manager of the IN Call Control function.
SSFDCF is the master of the size alteration events for call records and leg records and it informs the blocks holding call records when a record must be initialized and when it is dismissed.
SSFDCF contains a file for route data defined by command EXRBC. This data will be used as default route data when route-index is defined in oper-ations Connect and/or InitiateCallAttempt.
SSFDCF contains a file for IN service trigger (IST) data defined by com-mands SWIPI, SWITI and SWRDI. IST data is used to arm trigger detec-tion points (TDP) and indicates which operadetec-tion InitialDP or
AssistRequestInstruction is to be send when the TDP is encountered in the call. Furthermore holds each TDP information about which contents the InitialDP should have if a call encounters the TDP and to which SCF the operation should be send to.
SSFDCF contains a file for destination route data defined by command SWSDI. These destination is used to route the InitialDP or AssistRequest-Instruction operations to the right SCF according to the destination indi-cated on a given trigger detection point on the IST.
When SSF is seized from TCS, SSFDCF is linked to RE where it reads the necessary data. After the reading SSFDCF is replaced in the traffic chain by SSFCCF.
SSFDCF stores the data received in operations from the Service Control Function and ’IAM’ data read from TCS (or through TCS).
When a trigger detection point is encountered, the SSFDCF will send either InitialDP or AssistRequestInstruction to the SCF with requested information according to the trigger data.
SSFDCF supplies data for operation sending as well as ’IAM’ data for rout-ing.
3.9.2 SSFCCF
SSFCCF have two interfaces towards TCS, an IT- and an OT-interface.
When SSFDCF has send either InitialDP or AssistRequest
operation to SCF (or it realized that no originating TDP exists) SSFCCF is linked into the traffic chain instead of SSFDCF.
SSFCCF receives, queues and handles signalling events.
SSFCCF contains a filter towards signalling events.
SSFCCF reports events such as detection points to SSFEC. The call processing is halted for the actual call during the event handling in the
received signals - except disconnection signals - to and from the actual leg are buffered.
On order from SSFCROH, SSFCCF creates new outgoing legs. SSFEC takes care of the initialization of the leg records and informs the blocks holding the leg records, when a leg record must be initialized.
SSFEC administrates the token for the SSF. To prevent interactions when handling a received operation or an encountered detection point, a token is introduced. The token can be requested by any function at any time during the call. If the token is in use, the request will be added to a queue.
SSFEC maintains a CLSM on each leg. Every time an event is reported from SSFCCF/SSFDCF, SSFEC will update the CLSM on the leg on which the events has happened and if necessary also on the opposite leg.
Events are reported to SSFEC by all other blocks in the SSF that normally handles the events. The events can be that a detection point is meet or that a local event has happened. SSFEC handles the arming, disarming and reporting of different kind of events. When an armed event has occurred, SSFEC will inform all blocks that has asked for (armed) the event. If the event is a detection point, then SSFEC will occupy token before reporting the event. If the event is a local event the user must itself ask for the token if necessary.
When a the handling of a detection point is finished, SSFEC will check the remaining armings to update the Call FSMs, the Session FSM and check if the dialogues should still be kept open.
SSFEC handles the operations RequestReportBCSMEvent and CallInfor-mationRequest.
EventReportBCSM: SSFEC is requested for certain information when certain call events happens. The information is send to the SCF in opera-tion EventReportBCSM.
CallInformationRequest: SSFEC is requested for certain information when the call or a call leg disconnects. The information is send to the SCF in operation CallInformationReport.
3.9.3 SSFCROH
SSFCROH handles the operations from SCF that affects the call process.
The operations are CollectInformation, Connect, ConnectToResource, Continue, EstablishTemporaryConnection, DisconnectForwardConnec-tion InitiateCallAttempt and ReleaseCall.
CollectInformation operation: SSFCROH checks in SSFEC that DP2 (CollectedInfo) has been armed and that a number of required digits are specified. SSFCROH orders SSFEC to change the CLSM state to PointIn-Call CollectInformation.
Connect operation: SSFCROH orders SSFCCF to set up an outgoing leg to a new destination and connect it to an already existing initial leg
(incom-ConnectToResource operation: SSFCROH informs SSFSRF to prepare for announcement sending, text sending or digit reception.
Continue operation: SSFCROH informs SSFCCF to continue the call processing after an InitialDP or an EventReportBCSM has been send to the SCF. If no outgoing leg exist, SSFCCF will continue by making an outgoing leg (implicit Connect). If outgoing leg exist SSFCCF will propa-gate the reported event and release buffered events.
SSFCROH will also inform SSFEC that the call processing continues.
SSFEC will act as if handling of an event is finished.
• DisconnectForwardConnection operation: SSFCROH disconnects the connection towards the Assisting SSF.
• EstablishTemporaryConnection operation: SSFCROH uses an IT-inter-face towards TCS to set up a connection to an Assisting SSF.
• InitiateCallAttempt operation: SSFCROH orders SSFCCF to create an outgoing leg with no connection to another leg. This is only possible as the first leg in a call.
• ReleaseCall operation: SSFCROH orders SSFCCF to disconnect both incoming and outgoing leg. If a temporary connection exists, it will be disconnected as well.
3.9.4 SSFCHM
SSFCHM provides SSF with an interface towards CHS, so that SSF is able to hold and resume charging, provide charge limit check and to store charging information in the TT records and determine charging.
SSFCHM handles the operations SendChargingInformation, Furnish-ChargingInformation, ApplyCharging and RequestNotificationChargin-gEvent.
• SendChargingInformation: SSFCHM will order to send charging infor-mation in the traffic link (tariff, charge indicator etc.).
• FurnishChargingInformation: SSFCHM will send charging information directly to the charging instance for the call/service (tariff, additional billing information etc.).
• ApplyCharging: SSFCHM is ordered to request charging related infor-mation from CHS at a certain event. The inforinfor-mation is send to the SCF in operation ApplyChargingReport.
• RequestNotificationChargingEvent: SSFCHM is ordered to monitor for certain charging messages in the traffic link. The content of the charg-ing messages are returned to the SCF in the operation EventNotifica-tionCharging.
3.9.5 SSFICFH
SSFICFH is a help function for clearing of calls in error situations. A Clearing program is invoked that defines the actions to be taken e.g.
dis-The actions or sequence of actions can for each fault/clearing case be spec-ified by exchange data settings in the SSF.
Depending on the clearing program parameters and the state of the call, SSFICFH decides whether the call is to be released or, if possible, contin-ued.
3.9.6 SSFTDA1
SSFTDA1 handles a part of the command reception and printout of trigger table and traffic related data as well as service data, e.g. for setting of IN trigger analysis data. The rest is handled by SSFTDA2.
Commands SWIPE
Service Switching IST Procedure End
Terminates the specification of an IN service trigger.
SWIPI
Service Switching IST Procedure Initiate
Initiates the specification procedure of an IN service trigger (IST).
SWIDI
Service Switching IST Data Initiate
Defines the IN service trigger default settings.
SWISE
Service Switching IST Settings End
Removes IN service trigger data settings from the not operating area.
SWISP
Service Switching IST Settings Print
Print all data for one or all IN service triggers (IST).
SWITI
Service Switching Invoke Table Initiate
The command defines a Invoke Table. The purpose of the Invoke Table is to define which parameters should be send to the SCF when a dialogue is opened.
SWRDI
Service Switching Routing Data Initiate
Defines the Routing Table and connects the Routing Table to a specific Trigger Detection Point. The purpose of the data in the Routing Table is to secure that the correct SCF and Service Logic Program is invoked.
SWTDE
Service Switching Trigger Detection End
Removes a specified Trigger Detection Point and all connected data like Invoke Table and Routing Data.
Printout
- SSF IN SERVICE TRIGGER DATA 3.9.7 SSFTDA2
The block SSFTDA2 implements a part of the command initiated func-tions to administer IN service trigger data. The block handles command reception and printout for IN Destination data and Exchange data. The rest is handled by SSFTDA1 Further it handles commands used to copy, clear or switch the operating area (OP) and the not operating area (NOP) in block SSFDCF.
Commands SWTZI
Service Switching Trigger Zeroing, Initiate
Initiates zeroing of the entire not operating area for IN service trigger anal-ysis.
SWTCI
Service Switching Trigger Copy, Initiate
Initiates copying of the operating area for IN service trigger analysis to the not operating area.
SWTAI
Service Switching Trigger Activate, Initiate
The command activates IN service trigger data which previously has been setup by several initiating commands.
SWTAR
Service Switching Trigger Activate, Reset
Initiates a switch to previously used IN service trigger data, if the protec-tion period has not elapsed.
SWPTI
Service Switching IN Service Trigger Procedure, Initiate Clears the protection time on the not operating area.
SWSDI
Service Switching Service Control Function Destination, Initiate Defines destination data to be used when routing against SCP.
SWSDE
Service Switching Service Control Function Destination, End
Removes a SCP destination of the type DPC or GT logical. SWSDP Prints data for one or all of the defined SCP destinations
SWSEC
Service Switching Exchange Data, Change
The command is used to set IP SSP Capabilities and location of cause originator (LOC) parameters or default values for operation types Initiate Call Attempt, Establish Temporary Connection and Connect.
SWSEP
Service Switching Exchange Data, Print Initiates a printout of exchange data.
Printouts
- SCF DESTINATION DATA - SSF EXCHANGE DATA
- IST USED IN B-NUMBER ANALYSIS, LINE BASED SERVICES OR CALL IN PROGRESS.
3.9.8 SSFSFA
SSFSFA handles the commands and printouts in conjunction with service filtering.
Commands SWFPI
Service Switching, Service Filtering Procedure, Initiate Initiates the specification procedure for Service Filtering data.
SWFPE
Service Switching, Service Filtering Procedure, End Terminates the Service Filtering specification procedure SWFSI
Service Switching, Service Filtering Specification, Initiate
Specifies Service Filtering data for a given Service Filtering Criteria.
SWFSE
Service Switching, Service Filtering Specification, End Removes data for a specific Service Filtering Criteria.
SWFSP
Service Switching, Service Filtering Specification, Print
Initiates printout of Service Filtering Criteria, data and counters.
Printouts
- SERVICE SWITCHING SERVICE FILTERING RESULT
3.9.9 SSFCGA
SSFCGA handles the commands and printouts in conjunction with call gap.
Commands SWGPE
Service Switching Call Gap Procedure, End
Terminates the specification procedure for Call Gap data.
SWGPI
Service Switching Call Gap Procedure, Initiate
Initiates the specification procedure in order to specify Call Gap data.
SWGSE
Service Switching Call Gap Specification, End Removes data for a specific Call Gap criteria.
SWGSI
Service Switching Call Gap Specification, Initiate
Specifies Call Gap data for a specific type of Call Gap criteria.
SWGSP
Service Switching Call Gap Specification, Print Initiates printout of Call Gap Criteria and data.
Printouts
- SERVICE SWITCHING CALL GAP DATA 3.9.10 SSFCG
SSFCG protects the SCF against overload by rejecting calls in the SSF according to Call Gap mechanism.
SSFCG handles the operation CallGap.
3.9.11 SSFSF
SSFSF provides a mechanism to reject calls either on basis of an interval specification or on basis of number of calls.
SSFSF handles the operation ActivateServiceFiltering 3.9.12 SSFSRF
The block handles and controls the interface towards announcement equipment and gives directives towards the IN Call Control. SSFSRF han-dles the operations PlayAnnouncement and PromptAndCollect.
For both operations it is possible to play an announcement, send a tone or a text. When e.g. an announcement is to be played or a tone is to be send on a leg, SSFSRF will select the announcement device and control it. Then
it will request the IN Call Control to set the proper state in the Leg Level FSM and establish the connection in GS.
When a text is to be send, SSFSRF will order SSFCCF to send the text in a xxx message in the traffic link.
3.9.13 SSFDM
This block is responsible for handling (opening, closing and supervision) of dialogues. SSFDM is the connection between the Protocol Handler and the operations handlers in the SSF. SSFDM administrates all operation reception and operation sending to and from the SSF. SSFDM maintains a table for distribution of operations and distribute the operations to the right operation handlers. SSFDM collects operations from the SSF to the SCF so that they are send in the most efficient way (as many operation in one message as possible).
SSFDM handles the operation Cancel. When InvokeID is specified, SSFDM will order SSFSRF to cancel a specific operation. When ’ALL’ is specified SSFDM will order SSFEC and SSFCHM to cancel all outstand-ing reports to the SCF. The dialogue will not be closed even though no reports are outstanding. The SSF will wait for new orders from the SCF.
3.9.14 SSFXCM
SSFXCM has the interface from SSF to the group switch. SSFXCM con-nects and releases passes in the group switch in the
appropriate way for the situation. SSFXCM is ordered to connect or release passes from SSFCCF.
To change the passes in the group switch, SSFCHM also have the connec-tion to the call control funcconnec-tions (CLCOF). SSFXCM makes sure that both CLCOFs are updated with the correct MUPs and connections.
SSFXCM is not operation receiving.
3.9.15 SSFMCS
SSFMCS handles the traffic part of the Call Gap and the Service Filtering functions and the connection to the special resource functions (SRF).
3.9.16 Link Pictures
Figure 3.10
Call accessing SSF - before full number is received.
Figure 3.11
Call accessing SSF - full number is received. An InitialDP is send to the SCF.
inc.
trunk CHS TCS SSFDCF
SSFXCM
SSFCHM SSFCCF
SSFEC
inc.
trunk CHS TCS
SSFXCM
SSFCHM
SSFCCF
SSFEC