Cisco IP Phone 6821 Multiplatform Phones Fail to Upgrade or Get Stuck in a Reboot Loop While Attempting to Register to a Call Controller
What is the problem?
When attempting to onboard a Cisco IP Phone 6821 Multiplatform Phone, CP-6821-3PCC-K9, the device fails to upgrade or gets stuck in a reboot loop. The device is also slow or unresponsive when the keypad or the web interface are used.
Some Cisco IP Phone 6821 Multiplatform Phones were released from the factory with an issue that causes the symptoms that are described above. To resolve this issue, update the firmware to Release 12.0(3)SR2.
This issue is documented under the Cisco bug ID CSCwm86242.
How do I know if my product is affected?
CP-6821-3PCC-K9 phones with version ID (VID) = 06 and serial numbers FVH28250V0Q, FVH28250V0R, or FVH282707DV to FVH283948SS inclusive are affected. These phones were manufactured between 2nd July 2024 and 5th September 2024 inclusive.
What is the workaround/solution?
To resolve this issue, upgrade the phone to firmware Release 12.0(3)SR2 (12-0-3MPP0203-204) before moving to another version or onboarding to a call control system. Use the following instructions to recover the phone manually and upgrade it to firmware Release 12.0(3)SR2 (12-0-3MPP0203-204).
Note: If the phone has been onboarded to Webex Calling or registered to another call control system, perform a factory reset before using the following steps.
- Step 1. Power on the phone and connect the network cable to the ethernet port of the phone
- Step 2. Verify that the phone gets an IP address
- Step 3. Browse to the web interface of the phone at http://<PHONE_IP>/admin/advanced
- Step 4. Choose Voice > Provisioning
- Step 5. In the Upgrade Rule field, enter http://52.26.82.54/6821_load/sip6821.12-0-3MPP0203-204.loads
- Step 6. Click Submit All Changes
The phone will upgrade and boot up on firmware Release 12-0-3MPP0203-204. At this point, the phone may be upgraded to another firmware release or continue onboarding to a call control system.
The above IP will need to be allowed through any firewall based equipment. The server is controlled by Cisco, hosted in AWS.
Warning - under no circumstances try to upgrade the device to anything other than 12.0(3)SR2 (12-0-3MPP0203-204). Doing so may result in the device becoming unrecoverable and the device needing to be RMAed.
Batch recover phones by DHCP option
- Step 1. Upload the file 6821_upgrade_only.xml (provided in this article) to a HTTP/HTTPs server. Then configure DHCP option 160 to http://<HTTP.server.url>/6821_upgrade_only.xml. TFTP can also be used in the same way
- Step 2. Connect the Ethernet cable to the phone and power it on, phone will apply the DHCP option and start upgrading process automatically
- Step 3. After the upgrading is completed, check the phone’s software version through LCD Settings -> Status -> Product information -> Software version and make sure it is sip6821.12-0-3MPP0203-204
- Step 4. It is not required but if you want to restore the phone to Out Of Box state, factory reset the phone
- Step 5. Remove DHCP option 160 after all the phones are recovered
Contents of 6821_upgrade_only.xml:
<?xml version="1.0" encoding="UTF-8"?>
<device>
<flat-profile>
<Upgrade_Rule>http://52.26.82.54/6821_load/sip6821.12-0-3MPP0203-204.loads</Upgrade_Rule>
</flat-profile>
</device>
Automatically recover via EDOS/CDA short activation code
This can be used for Webex Calling or Non Webex Calling devices.
- Step 1. Connect the Ethernet cable to the phone and power it on
- Step 2. Input “#682106” on the activation code screen on Phone LCD then press “Continue” soft key
- Step 3. After the upgrading is completed, check the phone’s software version through LCD Settings -> Status -> Product information -> Software version and make sure it is sip6821.12-0-3MPP0203-204
- Step 4. If the phone is on Webex Calling, restore the phone to out of box state by doing a factory reset; otherwise, a factory reset is optional
For a Webex Calling device, normal activation code onboarding can then be used to onboard the phone. The content of the #682106 activation code is owned and maintained by Cisco.
Automatically recover in WxC
If the phone has already been attempted to be onboarded, perform a factory reset first. You can onboard 6821 VID 06 phones as usual if the phone is still in the out of box state/brand new/has been factory reset.
- Step 1. Setup the phone by MAC address as usual on Control Hub
- Step 2. Connect the Ethernet cable to the phone and power it on
- Step 3. The phone will then zero touch redirect via EDOS to Webex Calling which has a logical fix in place to point the phone first to 12.0.3SR2 if the phone being onboarded is running 12.0.3. In this case there will be two upgrades. One to 12.0.3SR2 and then another to the currently running Webex Calling firmware release
