I am unable to activate the extension mobility option on IP phone,
it gives an error saying "Update failed. One of the required fields on the page has the same value as an entry that already exists in the database. Please check the corresponding Find List page to verify your entry does not exist."
I already tried deleting and adding the phone again to the call manager, but this error recures back, the call manager version is 22.214.171.1240-3
Note: this error hits on only 1 of my IP phone.