Gigaset does not make it compulsory for customers to update the firmware of the devices. That is why we stick to such Brand's policy and do not make Gigaset devices upgraded to the latest firmware version in auto provisioning automatically.
To upgrade a firmware it is needed to go to the webinterface of the device, go to the section "Management" -> "Firmware update".There you will find the latest available firmware version.
By clicking the button "Update firmware" the firmware version which is currently supported in provisioning will be pushed to the device.
You can check on the firmware versions for Gigaset devices we support in auto provisioning at Which firmwares are supported in the auto provisioning?