Hi Cheryll,
Are you still having this issue? What's the exact error on the touch panel? By far the most common reason for an "Unable to retrieve the boot image" error is an incorrect Phone Load Name on CUCM. Make sure the load does not have .SPA, .loads, or .sbn at the end of it, it should just look like "CTS.1-10-2-42R-K9.P1".
If your error is "Establishing Connection", check out this article: https://supportforums.cisco.com/docs/DOC-28757
Other things to make sure:
1. Are you using the power injectors (and are they receiving power?)
2. The TFTP service was rebooted on CUCM following the most recent software upgrade
3. The MD5 was verified on the most recent software upgrade
4. If you're running 1.9.0 or earlier, make sure DNS is configured on the codec and you can resolve the hostname of CUCM. This was fixed in later versions of 1.9: CSCua03327
5. Port 6970 needs to be open between the CTS and CUCM
6. Is the codec DHCP service dead? You can check with "utils service list" from the CLI.
Tyler
