LST ETS 300 185-4 Leid.1-2007 Integrated Services Digital Network (ISDN); Telefonkonferenz, Zusatzdienst (CONF); Protokoll Digital Subscriber Signaling System No
2007LST ETS 300 185-4 Leid.1-2007 Integrated Services Digital Network (ISDN); Telefonkonferenz, Zusatzdienst (CONF); Protokoll Digital Subscriber Signaling System No