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Strategy for managing phone firmwares


I would like your advice on phone firmware management.

We are running a big CUCM 8.6 cluster with many site offices. The phone firmware version in device defaults is 9.3

When we order new phones,  we receive phones with firmware versions less than 9.3 and greater than 9.3.

When the firmware version is less than 9.3, we dont have an issue. The phones just upgrade.

When the firmware version of the new phones is greater than 9.3, then we have had issues.  Phones dont do the downgrade of the firmware from a higher version to a lower version. Does Cisco support downgrade of the phone firmware from a higher to a lower version? How do we know which version downgrades have been tested by Cisco. I dont see much info about downgrade in the release notes.

How do we manage this situation?

We dont want to add the new devices with a special load as we would like all devices in our network to have the same load.

Is upgrading the phone firmware globally on CUCM on a regular basis the only solution?

Please let me know how you manage the issue of phone firmwares on CUCM?

Many thanks for your help!!



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Hall of Fame Super Red

Strategy for managing phone firmwares

Hi Pete,

Just to add some new fun into things, you now have to watch for

new "Hardware" versions as well. This will also impact the upgrade

& downgrade determinations made by certain phones when they

look to register. So your new phones won't downgrade to the older 9.x version and

this is why you are seeing these anomalies

So if you move past 9-3-1sr1 in the general device defaults you should be good to go.

Hardware Updates

The hardware updates improve the compatibility of internal phone components.

The following table lists the updated hardware versions that require this release.



Hardware Version

Cisco Unified IP Phone 7942G

15.0 and higher

Cisco Unified IP Phone 7962G

15.0 and higher

Cisco Unified IP Phone 7945G

13.0 and higher

Cisco Unified IP Phone 7965G

13.0 and higher

Cisco Unified IP Phone 7975G

12.0 and higher


Phones  manufactured with these hardware versions must run Firmware  Release  9.3(1)SR1 or later. The phone firmware does not allow the phone to be downgraded to releases earlier than Release 9.3(1)SR1.




"When it comes to luck you make your own  " 

- Springsteen

Community Member

Strategy for managing phone firmwares

Hi Rob,

I am a newbie to Cisco support forum and I am big fan of you. I am glad that you replied to my post. I wonder how you manage to respond to so much posts with great detail   Thanks a lot for your reply.

If I understand you correctly, if we set the device defaults to 9-3-1sr1  or higher, then downgrades will work (atleast for sometime till Cisco releases new hardware with different requirements). Is that correct?

We are mostly using 69XX phones in our organisation.



Hall of Fame Super Red

Strategy for managing phone firmwares

Hi Pete,

Welcome aboard to CSC my friend & thank you for your very kind words

As you can see from our first post and many threads here @ CSC phone

firmware upgrades and downgrades can be very tricky. They probably

shouldn't be......but they are.

My info related to the hardware versioning probably isn't what is impacting

your 69xx series of phone models and their ability to downgrade, but it does

highlight why you need to always do your "due diligence"

Your issue is more likely related to "signed" firmware files that were introduced

to the 6900's somewhere around 9-0-2. If you are trying to downgrade newly

received phones to non-signed files it just won't happen as shown in this clip;

"After you upgrade from firmware release 8.5(4) to 9.0(3a) and for  subsequent firmware releases, you can upgrade or downgrade only to  signed firmware releases."


So we can see that you want to keep up to date with firmware upgrades as a general rule

to prevent issues that may cause what you are seeing along with the "intermediate" 2-hop

upgrades that come along if you get too far behind. It's also very helpful if all your phones

are running the same/consistent firmware just for ease of troubleshooting. So, best to move the

older firmwares up rather than moving down the ladder with them.



"When it comes to luck you make your own  " 

- Springsteen

Community Member

Strategy for managing phone firmwares

Hi Pete and Rob,

I too am having the same issue. I am about to upgrade to new 7945's replacing older 7940's and 7941's.  I currently have about 17 7945's running 45.9-3-1-1S in a call center. The new 7945's have 45.9-3-1-RS1. They wont downgrade when trying to add them.

Here is my question...Can I go ahead an put the newest firmware in the device defaults, and put the old firmware in the phone load on the existing phones in the call center thus preventing them from upgrading the firmware?  Is that an option? Does the phone load name field override the device defaults?

This way I should be able to get the new phones registered without taking the call center down.

Does this make sense?



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