$curl = curl_init();

curl_setopt_array($curl, array(
  CURLOPT_URL => 'https://wv{{wolkvox_server}}.wolkvox.com/api/v2/whatsapp.php?api=send_message_mobil',
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => '',
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 0,
  CURLOPT_FOLLOWLOCATION => true,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => 'POST',
  CURLOPT_POSTFIELDS =>'{
    "connector_id": "1",
    "telephone": "9319xxxxxxx",
    "message": "It is a message",
    "url_attach": ""
}',
  CURLOPT_HTTPHEADER => array(
    'wolkvox-token: {{token}}',
    'Content-Type: application/json'
  ),
));

$response = curl_exec($curl);

curl_close($curl);
echo $response;