The on-hook updates are not CTI-dependant. These are pushed from CUCM to CUP through the PUBLISH SIP trunk. If there is a delay in updates I suggest we start there.
What is the destination defined on the SIP PUBLISH trunk in CUCM? Is the destination SRV-based, A-record DNS, or an IPv4 address?
If DNS: Does it always resolve to one CUP server or is there a round-robin response?
If SRV: What format is the destination in on CUCM and CUP under the presence gateway?
Is the PUBLISH trunk choosen properly under callmanager service parameters?
You'll probably be best off to turn on troubleshooting traces of the CallManager process, reproduce the issue, and pull the SDI logs. We need to see what is happening to the SIP dialog between CUCM and CUP. For example, how long after the digit analysis before the SIP event is sent to CUP?
We can review logs if you attach them. Be sure to point out the CUCM hostname and IP, CUP hostname and IP, what phone IP and extension went off-hook, and when they went off-hook vs. when CUPC status updated.
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.