The LIT-1
ISA’s Line Impedance Test Set

LIT-1 Line Impedance Test Set

Designed for residences and small businesses, ISA’s Line Impedance Tester, codename LIT-1, is a highly reliable and dependable detector of eavesdropping devices on telephone lines. It offers a more complete and detailed analysis of telephone lines where tip and ring phone service is used; typically small key and Centrex type systems. The LIT-1 allows the operator to verify the results of on-hook and off-hook voltage tests made at the telephone or demarcation point.

Why The LIT-1?

Well, if you only measure voltages, there is no way to be certain that the readings do not reflect the changes caused by a series transmitter or parallel tape recorder switch because there are usually no other lines for comparison. A balanced telephone line will have, relatively the same impedance on both wires in the pair. Since significant differences in the impedance of each wire in the pair typically indicates the presence of an eavesdropping device, impedance testing of phone lines is the only reliable method to detect a listening device’s threat. The LIT-1 enables you to detect any changes that occur on one or both of the wires in the telephone pair that can indicate the presence of eavesdropping paraphernalia.