To downgrade IP Phone 7821 to firmware version 9

[sandych]

I Need to downgrade the firmware version of my new version latest 7821 ip phone to firmware version 9 for compatability with existing IP Phones and CUCM , , , ,Need to know can we do it and in a effective way if we do so can we use all the existing feature without any drawback.

[Leo Laohoo]

Note even remotely possible. The "earliest" firmware is 10.1(1)SR1.

[Jaime Valencia]

Not to mention that new features are only available on newer releases, you cannot expect to keep them if you downgrade.