Add multiple customer records to an existing campaign in a single request with optional call initiation.
Bearer <your_token>).true, initiates calls for all successfully added customers. Requires callConfig. Calls are triggered in batches of 500 after all records are added.initiateCall is true.true if all records were added successfully, false if any failed.initiateCall was true.201 — All records added successfully207 — Partial success (some added, some failed)400 — All records failed or validation error