Initiate a batch call operation using a CSV file and specified agent
{"enabled": boolean, "maxAttempts": number, "gaps": [{"days": number, "hours": number}]}phone_number - The phone number to call (required)first_name - First name for personalizationlast_name - Last name for personalizationemail - Email address400 - No file uploaded, no agent ID provided, or CSV validation failed413 - File size exceeds 20MB limit500 - Failed to prepare batch or start batch execution