Basic call state model

In Intelligent Network and CAMEL switching, a BCSM is a Basic Call State Model.^[1]

Types

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 call

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

O-BCSM

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