need to register back a 7911 from cucm 12 to cme 8?

[baselzind]

im working on a migration from cme 8 to cucm 12 , the problem i tested a phone which was previously on cme and got it on cucm 12 but now the customer needs the phone back on cme , after i factory reset the phone it is becoming stuck at upgrading , i think the version the 7911 got on cucm 12 cant go back to cme 8 which is as below:

cucm 12:SCCP11.9-4-2SR3-1S

CME 8:SCCP11.8-5-3S 

is there a middle version i should roll back the 7911 on cucm 12 before i roll it back to the cme? how can i register the phone back into the cme?

[HARIS_HUSSAIN]

Just upload the Firmware in Router flash configure proper load command in CME. Also make sure to add proper Option 150 pointing to CUCME address in DHCP Server.

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Thanks,
Haris

[baselzind]

i really cant touch the cme as it live , can i get the phone on cucm 12 to the same cme version and get it to register on cme?

[Maren Mahoney]

If the factory firmware in the phone is older than 8.3(3), you will need to upgrade to 8.5(2) before you can upgrade to 8.5(3) (or later) according to the release notes for the 8.5(3) firmware. Is it possible your phone is old enough to have pre-8.3(3) firmware?

Installing Firmware Release 8.5(3) for SCCP - Firmware Upgrade Issues for SCCP

Maren

[baselzind]

well right now the phone is on 9.4 but i need to get it back to 8.5 which is unable and getting stuck in upgrading

[Maren Mahoney]

If you did a factory reset, it would have wiped out the firmware it downloaded from CUCM and failed back to the firmware in the non-writable partition of the flash. (Which I can guarantee is not 9.4.)

If you did not do a factory reset, the phone will not downgrade and it is possible that the firmware that it downloaded from CUCM is not compatible with CME 8.x. That is unlikely, but possible. I'd have to do some research.

Maren