curl --request GET \
  --url https://api.wabox.me/instances/{instance_id}/token/{token}/phone-exists/{phone}

const options = {method: 'GET'};

fetch('https://api.wabox.me/instances/{instance_id}/token/{token}/phone-exists/{phone}', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

import requests

url = "https://api.wabox.me/instances/{instance_id}/token/{token}/phone-exists/{phone}"

response = requests.get(url)

print(response.text)

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.wabox.me/instances/{instance_id}/token/{token}/phone-exists/{phone}",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "GET",
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"net/http"
	"io"
)

func main() {

	url := "https://api.wabox.me/instances/{instance_id}/token/{token}/phone-exists/{phone}"

	req, _ := http.NewRequest("GET", url, nil)

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

{
  "phone": "5511988887777",
  "exists": true,
  "canonical_phone": "5511988887777",
  "jid": "5511988887777@s.whatsapp.net",
  "lid": "987654321098765@lid"
}

{
  "error": {
    "code": "instance_not_found",
    "message": "Instance not found or invalid token"
  }
}

{
  "error": {
    "code": "subscription_required",
    "message": "Active subscription required"
  }
}

{
  "error": {
    "code": "instance_not_connected",
    "message": "Instance is not connected"
  }
}