The phones will look at the device defaults section to see if a new firmware is available and download it. They will then download the load. If the new load is not available, it will fall back to the old load and the phone will register.
I know they how they will get the new load but all 2800 can not get the load at the same time. I do not want some coming up with the old load. Is there a way to make sure they all get the load and they do NOT come up with the old load? Do I just have to do a reset of the ones with the old load once the system is back up?
As long as the phones are not hardcoded at the device level with an older load then they will upgrade (assuming the current load is compatible) when they are reset. It sounds like you are more concerned about all the phones rebooting at once. If that's the case then you will need a way to reboot subsets of phones in an orderly fashion. At NetCraftsmen, we use a custom script to do this which pulls IP phone registrations and sort them in a way that makes sense for the customer environment. The end result is we use BAT to reset groups of phones in a controlled manner to control the upgrade and load on the TFTP servers, etc. As noted before, you can do this via Device Pools, device types, or you can also sort out some custom BAT files to do the same on your own. The only caveat is that any phone that gets reset in the interim (whether from CUCM or otherwise) will upgrade either way.
When you install the latest firmware on all nodes within the cluster, it will automatically change the Device default section of the firmware phone type that you uploaded. Phones will then need to be reset in order to get this new firmware release.
The easier way to do a massive phone reboot will by by either restarting the CCM service on the nodes dedicated for call processing, or by rebooting the server itself. There is a third option which is to reset the Device Pools (DP) that way you have control about which endpoints to reboot first and if you want to have a specific order.
Another thing you can do is restart the endpoints by phone type. You will be able to achieve this by going into Device --> Phone and then search for the specific phone model that you would like to take the new firmware.
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.