HTTP Status Codes

Code	Meaning
`200`	Success.
`201`	Created.
`400`	Bad Request.
`401`	Unauthorized.
`403`	Access Denied.
`404`	Not Found.
`409`	Conflict — e.g. duplicate phone.
`413`	Payload Too Large.
`422`	Unprocessable Entity — schema or campaign-config validation.