Safety Certified Capacitors are used in large quantities in telecom applications utilizing RJ11 (standard phone line) connections. These applications include DSL and dial up modems, set top boxes, VoIP phones, point of sales terminals and fax machines. In telecom applications, Safety Certified Capacitors are used in two circuits. The first one is filtering EMI from the Tip and Ring lines to ground. A telephone line carries a lot of noise and must be filtered to meet EN 55024 requirements. The capacitors are used as EMI filters in this case. Since they bridge the isolation barrier between line and ground, they must be able to withstand any high impulse voltages that may come down the line. The capacitance values used in this application are usually between 100pF and 1000pF.