Hi Joe,
Multiple Lines Support:
Cisco Unified CCX provides multiple line support using the 6900/7900/8900/9900 series phones as agent devices. The Join Across Line (JAL) and Direct Transfer Across Line (DTAL) operations are supported on the 7900/8900/9900 series phones. Up to 4 lines are monitored by Cisco Unified CCX, these include 1 ACD line and 3 non-ACD lines but only the ACD line can be controlled from the agent desktop. The agent state depends only on the ACD line on the agent's device.
Cisco Unified CCX allows more than four lines to be configured on the agent device but monitors only the first four lines provided these lines are not shared. The ACD line should be among the first four lines. The Agent can perform JAL and DTAL operations for the ACD call only by using the monitored lines
Calls on the non-ACD lines can be displayed on Cisco Agent Desktop. Supervisors can also monitor, record, intercept and barge-in on all calls or only ACD calls, depending on configuration.
Please refer the page 46 onwards in the below link,
http://www.cisco.com/en/US/docs/voice_ip_comm/cust_contact/contact_center/crs/express_8_5/design/uccx851srnd.pdf
Hope it helps.
Anand
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