Press volume up. Reconnect headphones to the device. If neither of these suggestions work, you could also try connecting the headphones to a different device to make sure they are operating correctly.

If you need any further assistance with this question, please contact the Sonim Customer Experience Center at 1-833-MY-SONIM (1-833-697-6646) or email us at [email protected].  We are open 24 hours a day, Monday-Friday and we will further assist in troubleshooting.