curl --request POST \
  --url https://api.telli.com/v1/add-contacts-batch \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "contacts": [
    {
      "external_contact_id": "<string>",
      "first_name": "<string>",
      "last_name": "<string>",
      "phone_number": "<string>",
      "external_url": "<string>",
      "salutation": "<string>",
      "email": "[email protected]",
      "contact_details": {},
      "timezone": "<string>"
    }
  ]
}
'

{
  "total_processed": 4,
  "total_success": 3,
  "total_failed": 1,
  "result": [
    {
      "external_contact_id": "ext123",
      "status": "success",
      "contact_id": "a1b2c3d4-e5f6-7890-abcd-ef1234567890"
    },
    {
      "external_contact_id": "ext124",
      "status": "success",
      "contact_id": "b2c3d4e5-f6a7-8901-bcde-f12345678901"
    },
    {
      "external_contact_id": "ext125",
      "status": "success",
      "contact_id": "c3d4e5f6-a7b8-9012-cdef-123456789012"
    },
    {
      "external_contact_id": "ext125",
      "status": "error",
      "error": "External ID already exists, must be unique"
    }
  ]
}