Downgrade/erase firmware 9620

[rsnari]

How do I go about erasing the flash, or downgrading the firmware on a 9620L, or 9620C?

I have at least one phone that needs to have the incorrect software removed, and a couple that need to be downgraded.

They just ignore the files on the http server.

?

[afahmy]

this would be done using the group ID feature in the IP phones station form and applying that to the upgrade file with the different firmware versions that should be applied.

[jlux]

How to

Can you give instructions on how to do that exactly?