Problem in registering 9971 phones in CUCM 8.0?

Registration of some 9971 phones in a fresh  CUCM 8.0 environment fails constantly. The phones ran without problems  in another CUCM 8.0 before and have the "old" config still active  (because they never registered to the new cluster). The log of the  phones shows the following:

	21:08:06 Updating Trust List
	21:08:17 Trust List update failed
	21:08:27 TFTP-Error : ram/SEPD0574CF62596.cnf.xml

The phones get a dhcp lease and the xml config file is  also available on the TFTP server; hosts can reach each other. It seems  that they are stuck at the TFTP step of the boot process.When searched for this error and some hints were found towards possible authentication  problems (CTL List), but there was nothing special configured in the  cluster before (unsecure profile, i.e.). 

If the phone is not updating the trust list then you have to erase it manually because some time even after factory default reset it doesn't work.

Resetting the IP Phone CTL manually#

press settings ==> then **# to unlock the settings => then go to security configuration => Trust list => select the CTL file and press erase.

The phone will reset and wait for downloading the new CTL files from the tftp server.

More details and references can be found here.

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