Zdravím,tuto záležitost si musí vyřešit volaná strana nastavením hlasitosti,případně hledat aplikaci,která pomůže.https://www.google.com/search?q=zv%C3%BD%C5%A1en%C3%AD+zvuku+android&sca_esv=6caa5e356376fd75&sca_upv=1&source=hp&ei=xrf7ZtrcMfGN9u8PvqmluAY&iflsig=AL9hbdgAAAAAZvvF1l_w7heIbRhYPdXK_qN3oqD9AxPL&ved=0ahUKEwja19XH5uyIAxXxhv0HHb5UCWcQ4dUDCA8&uact=5&oq=zv%C3%BD%C5%A1en%C3%AD+zvuku+android&gs_lp=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&sclient=gws-wiz