Facing issues while creating the element template of Call Activity?

I am creating element template of CallActivity but I am not sure how we can provide “CallActivity Type” using the json file.
Things which I want to achieve using the json file:
i) Select “CallActivity Type” as BPMN
ii) Provide called element to the field which arrives after the above step.
iii) Provide Binding type to latest
iv) Check “Business Key” checkbox