Sometimes you troubleshoot the phone presence status issue, or you are wondering how the status is retrieved by IMP, the best place to start is to look at the SIP Publish message sent by the CUCM to IMP, Capture the SIP Publish message using wireshark, in the content verify that the content of SIP Publish message, the status of the users reported by CUCM to IMP is carried in the XML fomart :
<basic>closed</basic>
</status>
<r:activities><r:busy/></r:activities>
The "closed" word means that the phone is busy or not available.
When the user is available, the SIP Publish message content contains the word "Open" as shown below:
<status>
<basic>open</basic>
</status>
