Basic call state model

<h2 id="types">Types</h2>
<ul><li>O-BCSM (Originating BCSM)</li>
<li>T-BCSM (Terminating BCSM)</li></ul>
<p>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
</p>
<h2 id="state-machine-description">State machine description</h2>
<p>In the following IN BCSMs, bold Detection Points and Points In Call are also present in the CAMEL Ph1 subset. 
</p><p>TODO: Expand to Ph2,3,4
</p>
<h3>O-BCSM</h3>
<h4>Points in call</h4>
<ul><li>1. O_Null & Authorize Origination Attempt</li>
<li>2. Collected_info (Merged with 1. in CAMEL Ph1)</li>
<li>3. Analyze_Info</li>
<li>4. Routing & Alerting (Merged with 3. in CAMEL Ph1)</li>
<li>5. O_Active</li>
<li>6. O_Exception</li></ul>
<h4>Detection Points</h4>
<ul><li>1 Origination_Attempt_Authorized</li>
<li>2 Collected_Info</li>
<li>3 Analyzed_Info (this is the only Statically armed DP, others are dynamically armed using "Request Report BCSM (RRBE)" message by the SCP)</li>
<li>4 Route_Select_Failure</li>
<li>5 O_Called_Party_Busy</li>
<li>6 O_No_Answer</li>
<li>7 O_Answer</li>
<li>8 O_Mid_Call</li>
<li>9 O_Disconnect</li>
<li>10 O_Abandon</li></ul>
<h3>T-BCSM</h3>
<h4>Points in call</h4>
<ul><li>7. T_Null & Authorize Termination_Attempt</li>
<li>8. Select_Facility & Present_Call</li>
<li>9. T_Alerting (Merged with 8. in CAMEL Ph1)</li>
<li>10. T_Active</li>
<li>11. T_Exception</li></ul>
<h4>Detection Points</h4>
<ul><li>12 Termination_Attempt_Authorized</li>
<li>13 T_Called_Party_Busy</li>
<li>14 T_No_Answer</li>
<li>15 T_Answer</li>
<li>16 T_Mid_Call</li>
<li>17 T_Disconnect</li>
<li>18 T_Abandon</li></ul>
<h2 id="messages">Messages</h2>

<ul><li><a href="/facts/Initial_Detection_Point_(telephony)/o0sXXxvY">Initial Detection Point</a> (IDP)</li>
<li>RRBE (Request Report BCSM)</li>
<li>Event Report BCSM (ERB)</li>
<li>Connect (CON)</li>
<li>Continue (CUE)</li>
<li>Send Charging Information (SCI)</li>
<li>ACH (Apply Charging)</li>
<li>ACR (Apply Charging Report)</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>From GSM to LTE: An Introduction to Mobile Networks and Mobile Broadband, p. 58, at Google Books <a href="https://books.google.com/books?id=uso-6LN2YjsC&pg=PA58" target="_blank">https://books.google.com/books?id=uso-6LN2YjsC&pg=PA58</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
</ol>

Basic call state model open-in-new

Basic call state model