Basic call state model

In Intelligent Network and CAMEL switching, a BCSM is a Basic Call State Model.

Types
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 call
 * O-BCSM (Originating BCSM)
 * T-BCSM (Terminating BCSM)

State machine description
In the following IN BCSMs, bold Detection Points and Points In Call are also present in the CAMEL Ph1 subset.

TODO: Expand to Ph2,3,4

Points in call

 * 1. O_Null & Authorize Origination Attempt
 * 2. Collected_info (Merged with 1. in CAMEL Ph1)
 * 3. Analyze_Info
 * 4. Routing & Alerting (Merged with 3. in CAMEL Ph1)
 * 5. O_Active
 * 6. O_Exception

Detection Points

 * 1 Origination_Attempt_Authorized
 * 2 Collected_Info
 * 3 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_Failure
 * 5 O_Called_Party_Busy
 * 6 O_No_Answer
 * 7 O_Answer
 * 8 O_Mid_Call
 * 9 O_Disconnect
 * 10 O_Abandon

Points in call

 * 7. T_Null & Authorize Termination_Attempt
 * 8. Select_Facility & Present_Call
 * 9. T_Alerting (Merged with 8. in CAMEL Ph1)
 * 10. T_Active
 * 11. T_Exception

Detection Points

 * 12 Termination_Attempt_Authorized
 * 13 T_Called_Party_Busy
 * 14 T_No_Answer
 * 15 T_Answer
 * 16 T_Mid_Call
 * 17 T_Disconnect
 * 18 T_Abandon

Messages



 * Initial Detection Point (IDP)
 * RRBE (Request Report BCSM)
 * Event Report BCSM (ERB)
 * Connect (CON)
 * Continue (CUE)
 * Send Charging Information (SCI)
 * ACH (Apply Charging)
 * ACR (Apply Charging Report)