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

{
  "contact_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a"
}