In the connection between a Cisco router and an E&M port on a PBX, which side is generally the Cisco side?
A.
loop start
B.
trunk circuit
C.
switch port
D.
signaling unit
Explanation:
Analog trunk circuits connect automated systems, such as a private branch exchange (PBX) and the network, such as a central office (CO). The most common form of analogtrunkingis the E&M interface. E&M Signaling is commonly refer to as “ear & mouth” or “recEiveandtransMit”, but its origin comes from the term earth and magnet. Earth represents electrical ground and magnet represents the electromagnet used to generate tone.
E&M signaling defines a trunk circuit side and a signaling unit side for each connectionsimilar to the data circuit-terminating equipment (DCE) and data terminal equipment (DTE) reference type. Usually the PBX is the trunk circuit side and thetelco, CO, channel-bank, or Cisco voice enabled platform is the signaling unit side.
Note:
Cisco’s analog E&M interface functions as the signaling unit side, so it expects the other side to be a trunk circuit.