Where is the phone located physically in regards to the CM server? This typically indicates network delay back to CM server, also make sure there are no DNS issue if you are using DNS, NIC bindings are set properly and that the server is not running in half duplex mode.
Physical location is one thing; however, the logical network placement is what the previous poster was referring to. Physically, you could place an IP phone on top of the CUCM but logically, it could be connected to the network and be 10 hops away from the CUCM. Ping from the source interface of your IP phone network to the CCM server and take note of the delay noted in the response. If they are on the same LAN and no routing issues, there should be minimal delay.
I tend to think that the OP has phones and CMM very close both physically and in network topology. Beside, even 10 hops on a campus network of today does not introduce any noticeable delay in using phone or applications.
What could be happening instead, is that the network is troubled, there are broadcast storms or other major disruption. This is just a supposition, the cause can even be different.
I performed a ping from the CallManager to the 7961 IP phone's IP address and to another IP phone and the delay was the same < 10ms and there is more than 500-600 IP phone in the network and this delay is in 7961 IP phone only
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.