I have several hundred Cisco 7900 series IP phones, (7911, 7942, and 7962 models) that have been sitting on the shelf as replacement stock for several years.

Now as we deploy them, we are experiencing some odd firmware issues. When they are booting up, the phones attempt to upgrade via TFTP to the current firmware specified in CUCM, but they fail and display "Auth Fail" on their screen. Then the phones reboot and come up on the previous factory firmware load on the device.

Am I running into a firmware bug of some kind?

  • CUCM 7.1.3
  • SCCP Firmware on phones 8.3(2)
  • How to Open in CUCM the cisco phone? what is CUCM ? I am facing the same issue
    – user19094
    Sep 17, 2015 at 11:51

3 Answers 3


Most likely this is caused by a phone running on a firmware older than 8.5(2) being upgraded to something newer. This is a known issue, documented in the release notes for SCCP firmware release 8.5.(2)SR1:

For all SCCP firmware upgrades from firmware release versions earlier than 8.3(3) to version 8.5(2)SR1 or greater, you must first upgrade your firmware to version 8.5(2). Once you have upgraded to version 8.5(2), you can upgrade your IP Phone to version 8.5(2)SR1 or later.

So, assuming you're using CUCM, you can approach this several ways.

I recommend uploading the 8.5(2) firmware files to your TFTP server. Once you have the 8.5(2) firmware on your TFTP server, you can do the following (Cisco has a more in depth "How-To" located on their Support Forums):

  1. Open device in CUCM, find the field "Phone Load Name" under Device Information.
  2. Manually assign the phone to use 8.5(2) firmware by entering "SCCPXX.8-5-2S" where XX is the model of the phone. (11 for 7911, 42 for 7942, etc. but note that 7962 and 7965 models still use the "42" or "45" firmware respectively.)
  3. Apply configuration and allow phone to upgrade to 8.5(2).
  4. Remove manual Phone Load entry, apply configuration again and phone will upgrade to current release specified globally in CUCM.

This will allow you to resolve the issue on a phone-by-phone basis.


Ensure that you have provisioned the phone in CUCM for the correct model of phone. I've accidentally cloned a 7940 config when I actually had a 7942 phone and get the "Auth Fail" message because it's trying to pull the wrong firmware.


Look at the release notes for the version you're trying to load. There will be a section about requirements to perform an upgrade. Sometimes you'll need to load an intermediate version to get to the latest. Others need a differently packaged bundle. (signed vs. unsigned, etc.)

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