In Intelligent Network and CAMEL switching, a BCSM is a Basic Call State Model.[1]O-BCSM (Originating BCSM)T-BCSM (Terminating BCSM)A fundamental concept for IN control is the basic call state model (BCSM). When a call is processed by an exchange, the call goes through a number of pre-defined phases. These phases of the call are described in the BCSM. The BCSM generally follows the ISUP signalling of a callO-BCSMPoints in call1. O_Null & Authorize Origination Attempt2. Collect_info (Merged with 1. in CAMEL Ph1)3. Analyze_Info4. Routing & Alerting (Merged with 3. in CAMEL Ph1)5. O_Active6. O_ExceptionDetection Points1 Origination_Attempt_Authorized2 Collected_Info3 Analyzed_Info (this is the only Statically armed DP, others are dynamically armed using "Request Report BCSM (RRBE)" message by the SCP)4 Route_Select_Failure5 O_Called_Party_Busy6 O_No_Answer7 O_Answer8 O_Mid_Call9 O_Disconnect10 O_AbandonT-BCSMPoints in call7. T_Null & Authorize Termination_Attempt8. Select_Facility & Present_Call9. T_Alerting (Merged with 8. in CAMEL Ph1)10. T_Active11. T_ExceptionDetection Points12 Termination_Attempt_Authorized13 T_Called_Party_Busy14 T_No_Answer15 T_Answer16 T_Mid_Call17 T_Disconnect18 T_AbandonMessagesbasic INAP call exampleInitial Detection Point (IDP)RRB (Request Report BCSM)Event Report BCSM (ERB)Connect (CON)Continue (CONT)Send Charging Information (SCI)ACH (Apply Charging)ACR (Apply Charging Report)==================================================================================http://telecomprotocols.blogspot.com.br/2012/09/intelligent-networks-in-and-camel.htmlIntelligent Networks (IN):- Intelligent Networks is a concept service intelligence resides in a central node called an SCP and SSPs (residing on Switches) relinquish control to this node at particular stages in a call so that appropriate service logic can be applied.Objectives of IN:- Increased Service Velocity / Speed of Deployment- Increased Range of Services- Evolvability from Existing Networks- Service & Vendor Independent Implementation- MSC just focuses on core job of call processingNetwork Before IN: Before IN application, there was messed network for every node:Network with IN: After IN implementation, Network is organised.Basic Concepts PIC and DPs & BCSM:Point In Call (PIC) : A state in a basic call state model.Detection Point (DP) : A point in basic call processing at which specific event is detected. Detection Points represent transitions between points in call processing (PICs). There are two types of DPs: TDP and EDP. EDP is also of two Type.-Trigger Detection Point (TDP): statically armed DP at which the MSC/SSP first contacts the SCP to request for instructions or to provide information about call events. Processing is suspended when the DP is encountered.-Event Detection Point -Notification (EDP-N): An EDP is a dynamically armed DP that is armed by the SCP. The call processing point at which the MSC/SSP must contact the SCP to notify it of an event. Processing is not suspended when encountering the DP.- Event Detection Point Request (EDP-R): This detection point is dynamically armed within the context of a CAMEL control relationship. Processing is suspended when encountering the DP and the gsmSSF waits for instructions from the gsmSCF.- Service Switching Function (SSF) This is co-located with the MSC itself, and acts as the trigger point for further services to be invoked during a call.- Service Control Function (SCF) This is a separate set of platforms that receive queries from the SSP.- Service Data Function (SDF) This is a database that contains additional subscriber data, or other data required to process a call.- Specialized Resource Function (SRF) or Intelligent Peripheral (IP) This is a node which can connect to both the SSP and the SCP and delivers additional special resources into the call, for example play voice announcements or collect DTMF tones from the user.Customized Applications for Mobile networks Enhanced Logic, or CAMELfor short, is a set of standards designed to work on either a GSM core network or UMTS network. They allow an operator to define services over and above standard GSM services/UMTS services. The CAMEL architecture is based on the Intelligent Network (IN) standards, and uses the CAP protocol and it is particularly effective in allowing these services to be offered when a subscriber is roaming.CAMEL Network Structure:CSI identifies if the subscriber requires CAMEL support. CSI identifies which gsmSCF to use for that CAMEL support. CSI contains information related to the Operator Specific Service (OSS) of the subscriber, for example the Service Key.Originating-CSI identifies subscriber as having originating CAMEL Services. O-CSI is stored in the VLR as part of subscriber data for roaming subscriber in the VLR area.Terminating-CSI identifies subscriber as having terminating CAMEL Services. T-CSI is fetched by the GMSC when the HLR of the called subscriber is being interrogated by the GMSC. Originating-CSI is sent to the GMSC for forwarding.CSI CONTENT -gsmSCF address: as an E.164 numberService Key : which identifies to the gsmSCF the service logic that should be used.Default call handling: that indicates how to proceed the call in case of error in the dialogue (release or continue).TDP list: that indicates on which Detection Point (DP) triggering shall take place. Only DP2 for O-CSI and only DP12 for T-CSI.DP2/ DP3 Trigger Detection Point:A-Party MSC VLR SCP B-Party============================================================Setup> SIOC(IN)-> DP2 (OCSI)Service Screened in first SIOC: COS, ODB (BAOC & BAOC roaming outside the HPLMN Country), BAOC, CUG, IN (O-CSI)Service screened in second SIOC: Remaining flavos if ODB and barring, LCO, OSSP screening.DP12 Trigger Detection Point:A-Party MSC HLR SCP B-Party============================================================IAM> SRI-> Service screened in 1st SRI: DP12Service screened in 2ndSRI: except IN all service. DP2 on Forwared forwarding Leg: In Call Forwarding, subscriber A calls subscriber B, who forwards the call to subscriber C. The forwarding leg to C is seen as a call origination (from B) as opposed to call termination of the call originated by A.A-Party MSC-A HLR SCP PSTN=================================================================IAM> SRI-> DP2 and DP12 on Forwarded forwarding Leg: In this example the subscriber B has been provisioned with both T-CSI service and O-CSI service. To simplify the diagram, the Terminating service makes no modification to the call set up and the Originating service is used to modify the CLI of the outgoing leg.A-Party MSC-A HLR SCP PSTN==================================================================IAM> SRI> Applying O-CSI to a call forwarded by CAMEL (T-CSI) : CAMEL can be used to forward calls, instead of using GSM Call Forwarding. It is possible to apply an O-CSI CAMEL service to the outgoing leg created by a CAMEL forwarding service.A-Party MSC-A HLR SCP PSTN===================================================================IAM> SRI-> ANSWER Event Detection Point- Notify:A-Party MSC HLR SCP PSTN==================================================================IAM> SRI-> -IAM->