public function dtmf($liveCallUuid, $digits, $leg = null)
    {
        if (empty($liveCallUuid)) {
            throw new PlivoValidationException(
                "Which call to send digits in? No callUuid given");
        }

        if (empty($digits)) {
            throw new PlivoValidationException(
                "digits cannot be null");
        }

        $response = $this->client->update(
            $this->uri . $liveCallUuid . '/DTMF/',
            [
                'digits' => $digits,
                'leg' => $leg
            ]
        );

        $responseContents = $response->getContent();

        if(!array_key_exists("error",$responseContents)){
            return new ResponseUpdate(
                $responseContents['api_id'],
                $responseContents['message'],
                $response->getStatusCode()
            );
        } else {
            throw new PlivoResponseException(
                $responseContents['error'],
                0,
                null,
                $response->getContent(),
                $response->getStatusCode()

            );
        }
    }