Please try the following:

You can run the historical report for "Agent State Detail Report" and look for the "Not Ready" entry of the agent at the time the agent went

Not Ready. Check the reason code for this entry.

If the reason code is 32763, the agent went Not Ready because of RNA. If the agent phone is configured on CallManager with auto-answer enabled, then this is likely a CallManager issue since the call is not answered in time.

If the reason code is 32759, the agent went Not Ready because the phone went out of service. Check to make sure the phone is still functional and that you can call the phone directly. If everything seems fine, it is most likely a temporary problem and the phone has since recovered. If the phone is still down, it is most likely a CallManager problem.

If the reason code is 32757, the agent went Not Ready because the phone

rehomed due to a CallManager failover. As long as the agent is able to go Ready after the failover, this is not an issue.

Also, the following unsupported configurations can also cause the agent to go "Not Ready"

Two lines on an agent's phone that have the same extension but exist in different partitions.

An ICD extension assigned to multiple devices.

Call waiting enabled on an ICD line.

No Cisco CallManager device can be forwarded to the ICD extension of an agent.

The ICD extension of an agent cannot be configured to forward to a

Cisco CRA route point.