The speaker button on your keypad cycles through different volume defaults when pressed. You can change these in the Sound Profiles section of your Settings.
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.