For the following items, which is the most common E&M type used outside North America?

A.
Type IV

B.
Type I

C.
Type II

D.
Type III

E.
Type V

Explanation:
E&M Type I This is the most common interface in North America.

* Type I uses two leads for supervisor signaling: E, and M.
* During inactivity, the E-lead is open and the M-lead is connected to the ground.
* The PBX (that acts as trunk circuit side) connects the M-lead to the battery in order to indicate the off-hook condition.
* The Cisco router/gateway (signaling unit) connects the E-lead to the ground in order to indicate the off-hook condition.

E&M Type II Two signaling nodes can be connected back-to-back.

* Type II uses four leads for supervision signaling: E, M, SB, and SG.
* During inactivity both the E-lead and M-lead are open.
* The PBX (that acts as trunk circuit side) connects the M-lead to the signal battery (SB) lead connected to the battery of the signaling side in order to indicate the off-hook condition.
* The Cisco router / gateway (signaling unit) connects the E-lead to the signal ground (SG) lead connected to the ground of the trunk circuit side in order to indicate the off-hook condition.

E&M Type III This is not commonly used in modern systems.

* Type III uses four leads for supervision signaling: E, M, SB, and SG.
* During inactivity, the E-lead is open and the M-lead is set to the ground connected to the SG lead of the signaling side.
* The PBX (that acts as trunk circuit side) disconnects the M-lead from the SG lead and connects it to the SB lead of the signaling side in order to indicate the off-hook condition.
* The Cisco router / gateway (signaling unit) connects the E-lead to the ground in order to indicate the off-hook condition.

E&M Type IV This is not supported by Cisco routers / gateways.

E&M Type V Type V is symmetrical and allows two signaling nodes to be connected back-to-back. 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 Cisco router / gateway (signaling unit) connects the E-lead to the ground in order to indicate off-hook condition.