curl --request POST \
  --url https://api.starleads.co/CampaignItem/{campaignId}/bulk-add-items \
  --header 'Content-Type: application/json' \
  --header 'X-Api-Key: <api-key>' \
  --data '
{
  "items": [
    {
      "phoneNumber": "<string>",
      "dataBag": {},
      "nextTryDate": "<string>"
    }
  ]
}
'

{
  "errors": [
    {
      "item": {
        "phoneNumber": "<string>",
        "dataBag": {},
        "nextTryDate": "<string>"
      },
      "errorDescription": "<string>"
    }
  ]
}