curl --request POST \
  --url https://api.parceltracer.com/v1/external/customers/ \
  --header 'Content-Type: application/json' \
  --header 'X-Api-Key: <api-key>' \
  --data '
{
  "name": "<string>",
  "phone_number": "<string>",
  "secondary_phone_number": "<string>",
  "email": "jsmith@example.com"
}
'

{
  "id": 9721,
  "name": "Yasser",
  "phone_number": "+9617322112",
  "secondary_phone_number": "",
  "email": "yasser@email.com"
}