code: private function getSoapClient($service, $method, array $parameters)
      {
          $timestamp = time();
          $nonce = uniqid(null, true);
  
          $soapClient = $this->client->buildSoapClient($service);
          $soapClient->setTimestamp($timestamp);
          $soapClient->setNonce($nonce);
          $soapClient->setSignature(array_merge($parameters, ['__method' => $method]), $this->client->getPrivateKey(), $service, $this->client->getEndpoint(), $timestamp, $nonce);
  
          return $soapClient;
      }
docs: Get the SOAP client and preset call parameters.
  
  @param string $service    WSDL service used for the call
  @param string $method     Method used for the call
  @param array  $parameters Parameters used for the call
  
  @return \TransIP\Soap\SoapClient