Use the RinglessHub upload API to push leads directly into an existing campaign.
Send JSON, include your API key in the request header, and pass one or more leads
in the leads array.
Send a JSON request to the upload endpoint with your campaign ID and lead array.
This is the cleaned-up version of the example you pasted.
Server-side PHP example using cURL.
Use this only from a secure backend or private environment.
Example JSON body structure.
Use these as documentation examples for success and error cases.