Manufacturers may also choose to include proprietary enhancements, e.g. Polycom’s Siren Audio extends the audio bandwidth up to 14kHz to improve the sound quality. These proprietary enhancements are not international standards so only provide a benefit when used between products from the same manufacturer. Proprietary standards should not be confused with ‘options’ within the ITUT standards. The options are not mandatory but when incorporated will allow improved compatible communication between dissimilar equipment without problems.