What we have tried so far in BAT did a phone wiery for device type contains 7841Clicked nextChecked apply config instead of dont reset/restart phones/ apply configChecked the box for wireless headset hookswitch controlToggled it to enableChecked run ...
We figured out that BAT will not work as we are still running version 11 of CUCM this causes the "String index out of range: -13" error to appear. Thank you all for the replies