/mcpIPPhone C has two lines, line1 (1002) and line2 (5003). 5003 represents an intercom line that is configured with Speeddial to 5002 with label ìAssistant_5002î. 4. IPPhone D has one line (5004). 5004 represnts an intercom line. 5. CTIPort X has two lines, line1 (2000) and line2 (5555). Line2 represents an intercom line. Speedial to 5001 gets configured with label ìAssistant_1î. 6. Intercom lines (5000 to 5003) exists in same partition = Intercom_Group_1 and they remain reachable from each other. 5004 exists in Intercom_Group_2. 7. Application monitoring all lines on all devices. Assumption: Application initialized and CTI provided the details on speeddial and lines with intercom line on all the devices. Behavior should act the same for phones that are running SCCP, and those that are running SIP. Application Invoking Speeddial Events Action For 5000 receive LINE_CALLSTATE cbInst = x0 param1 = x03000000 param2 = x1, ACTIVE param3 = x0, Receive StartTransmission event For 5001 receive LINE_CALLSTATE cbInst = x0 param1 = x03000000 param2 = x1, ACTIVE param3 = x0, Receive StartReception event Receive zipzip tone with reason as intercom LineOpen on 5000 & 5001 Initiate InterCom Call on 5000 Cisco Unified TAPI Developers Guide for Cisco Unified Communications Manager, Release 15 and SUs 862 Message Sequence Charts Application Invoking Speeddial