Please check the below points.
Unsupported Configurations for Agent Phones:
The following configurations are not supported for agent phones:
•Two lines on an agent’s phone that have the same extension but exist in different partitions.
•A Unified CCX extension assigned to multiple devices.
•Configuring the same Unified CCX extension in more than one device profile, or configuring the same Unified CCX extension in any combination of device profiles and devices. (Configuring an Unified CCX extension in a single device profile is supported.)
•In the Unified CM Administration Directory Number Configuration web page for each Unified CCX line, setting Maximum Number of Calls to a value other than 2.
•In the Unified CM Administration Directory Number Configuration web page for each Unified CCX line, setting Busy Trigger to a value other than 1.
•Configuring a Cisco Unified IP Phone with Secure Real-Time Protocol (SRTP) for use in silent monitoring and recording.
•No Cisco Unified Communications Manager device can be forwarded to the Unified CCX extension of an agent.
•The Unified CCX extension of an agent cannot be configured to forward to a Cisco Unified CCX route point.
•Use of characters other than the numerals 0–9 in the Unified CCX extension of an agent.
•Configuring the Unified CM intercom feature.
•Configuring the hold reversion feature.
