Type V is symmetrical and allows two signaling nodes to be connected back-to-back, as illustrated in Figure 7-4.This is the most common interface type used outside of North America. Type V uses two leads for supervisor signaling: E, and M. During inactivity the E-lead and M-lead are open. The PBX (that acts as trunk circuit side) connects the M-lead to the ground in order to indicate the off-hook condition. The IMACS-200 (signaling unit) connects the E-lead to the ground in order to indicate off-hook condition.
