Converting Cisco phone to SIP 3CPP

[mattmartini]

I recently purchased a Cisco CP-8851 phone to use with my Asterisk PBX. I already have a number of Cisco phones (8851 and 7960) working on this PBX.
The new phone has Call Manager software and it is looking to register with a call manager.

I want to change it to SIP 3CPP software.
The phone is currently running sip88xx.11-7-1-17 I want it to run sip88xx.12-0-6 (sip88xx.12-0-6MPP0001-65) like my other 8851.
When it boots up it requests its configuration from my TFTP server via the SEP<macaddr>.cnf.xml file. Or via XMLDefault.cnf.xml if
the SEP file is not found.

When I use the SEP<macaddr).cnf.xml file from my other 8851 phone (modified so the IP addr is unique) I get an "Error verifying config into" message in the phone's status messages.

Using a very simplified xml file I am able to get the phone to read the file and not throw an error, but it doesn't seem like any of the configuration takes effect.
I tried assigning a specific IP address

<Static_IP ua="rw">192.168.1.123</Static_IP>

, and turning on the web server interface

<Enable_Web_Server ua="na">Yes</Enable_Web_Server>

to no avail.

I tried this before and after resetting the phone to factory defaults.

What I really want to do is get the phone to load the upgraded software. I tried:

<loadInformation>sip88xx.12-0-6MPP0001-65.loads</loadInformation>

and

<Upgrade_Enable>Yes</Upgrade_Enable>
<Upgrade_Error_Retry_Delay>3600</Upgrade_Error_Retry_Delay>
<Upgrade_Rule>tftp://192.168.1.10/sip88xx.12-0-6MPP0001-65.loads</Upgrade_Rule>

But these didn't work. I never see a request for the loads file on my tftp server.

What is the minimal XML file I need to use to trigger an upgrade?