curl --request POST \
  --url https://api.scholarlysoftware.com/api/v1/profiles/{profile_id}/phone_numbers \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/vnd.api+json' \
  --data '
{
  "data": {
    "type": "phone_number",
    "attributes": {
      "label": "home",
      "phone_number": "+14155559012",
      "effective_from": "2023-12-25",
      "custom_fields": {},
      "external_id": "EXT-12345"
    },
    "relationships": {}
  }
}
'

{
  "data": {
    "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "type": "phone_number",
    "attributes": {
      "created_at": "<string>",
      "updated_at": "<string>",
      "custom_fields": {},
      "label": "home",
      "phone_number": "+14155559012",
      "external_id": "EXT-12345",
      "effective_from": "2023-12-25",
      "effective_to": "2023-12-25"
    },
    "relationships": {
      "user": {
        "links": {
          "related": "<string>"
        },
        "meta": {},
        "data": {
          "type": "user",
          "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a"
        }
      },
      "profile": {
        "links": {
          "related": "<string>"
        },
        "meta": {},
        "data": {
          "type": "profile",
          "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a"
        }
      }
    }
  }
}