This module has to be connected parallel to the telephone leads. It is an efficient protection for you and for your valuable telephone unit against overvoltages as happening during lightnings, static chargings, too high external voltages from the neighbourhood, etc. which may penetrate your telephone socket. It is possible that high voltages of more than (>) approx. 120V are deflected. Impulse circuit capacity up to 40 Ampere!
This module has no postal permission and should be used exclusively like a great deal of other telephone accessories within private telephone units without public exchange connection.