HLog and 6900 Series Phones

Unfortunately the 6900 series phones don't have any visible notification of whether or not the phone is logged into hunt groups. This means that once the message displayed after pressing the HLog softkey disappears, there's no way of telling if your phone will take calls from hunt groups, other than to press HLog again. This is a rather bizarre omission given that queuing on hunt pilots is one of the big new features in CUCM 9.x & that in 9.0 it actually automatically HLogs you out if you don't answer a call from a hunt pilot with queuing enable. Thus it's easy to get into a situation where no one is receiving calls from hunt groups & they have no idea why.
Thankfully in CUCM 9.1 you can disable the auto HLog out of phones via "Automatically Logout Hunt Member on No Answer" within the line group settings. But this still leaves 6900 series phones with no indication of HLog status. The solution is to use a custom phone button template with one of the buttons being the HLog PLK, for example:

The LED on that button then indicates whether or not the phone is logged in to hunt groups. This is actually pretty handy for 7900 series phones too, as their "Logged out of Hunt Group" status message gets overwritten by the number of missed calls status message.

Installing Updates With Invalid Licensing

If you try to install an update on to CUCM without valid licences installed it will block it & display the error message "Upgrades are prohibited during the licensing grace period". When you're midway through doing physical to virtual migration & major upgrade this can be a pain as Cisco GLO can take up to 72 hours to respond to licence migration requests.
Fortunately there is a way round this to get the patches installed & then go back to Cisco for licence migration. You'll need to download a CentOS minimal install ISO & boot the CUCM server from it, then follow these steps:

1. Select rescue installed system, skip the media check & select the appropriate language, keyboard layout, etc.
2. Select local CD/DVD & don't start networking
3. Select continue to mount the file system & continue through the information messages. If in doubt about which partition is active, you can boot off the CUCM Recovery DVD & use it to list the partition layout
4. Start the shell

From the shell run the following commands:

chroot /mnt/sysimage
cp /usr/local/platform/conf/licexpiry.txt licexpiry.txt.bak
rm /usr/local/platform/conf/licexpiry.txt

Next you need to stop SELinux from choking on the changes made to the filesystem, so we need turn off enforcing. Run the following command to locate the grub.conf files:

find ./ -name "grub.conf"

Now use vi to edit the grub.conf files & add enforcing=0 to the end of the line which says kernel, for example:

kernel /boot/vmlinuz-2.6.18-274.12.1.el5PAE ro root=LABEL=/partB clock=pmtmr divider=4 crashkernel=128M@16M enforcing=0

Now you can exit to reboot the server. Without licexpiry.txt present you can continue installing patches to get the desired version of CUCM.