Understanding and Troubleshooting Analog E & M Interface Types and Wiring Arrangements
成长的记忆Document ID: 8111
Introduction
Prerequisites
Requirements
Components Ud
Conventions
E & M Interface Supervision Signal Description
E & M Signaling Unit Side and Trunk Circuit Side Compatibility Issues
E & M Type I Interface Model
德庆龙母庙E & M Type II Interface Model
E & M Type III Interface Model
E & M Type V Interface Model
Troubleshoot E & M Interfaces at the Physical Level
Hardware Troubleshooting Tools
Precautions
Troubleshoot Type 1 Interfaces
Troubleshoot Type 2 Interfaces
Troubleshoot Type 3 Interfaces
Troubleshoot Type 5 Interfaces
Related Information
Introduction
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This document discuss the standard analog E & M interface types I, II, III, V (IV is not supported by Cisco platforms) and wiring arrangements. You can u this document as a troubleshooting reference for wiring problems between the router and private branch exchange (PBX)/Telco equipment.
Refer to Analog E & M Signaling Overview for an overview of Analog E & M.
Refer to Understanding and Troubleshooting Analog E & M Start Dial Supervision Signaling for information on E & M Start Dial Supervision signaling (wink, delay, immediate).
Prerequisites
Requirements
This document is intended for personnel involved with Voice over IP networks with basic knowledge of voice networks.
Components Ud
This document is not restricted to specific software and hardware versions.
婴儿补充dhaConventions
Refer to Cisco Technical Tips Conventions for more information on document conventions.渲
E & M Interface Supervision Signal Description
E (Ear or Earth) S ignal wire from trunking (CO) side to signaling side.
•
M (Mouth or Magnet) S ignal wire from signaling side to trunking (CO) side.
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SG (Signal Ground) U d on E & M Types II, III, IV (Type IV is not supported on Cisco router/
gateways).
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SB (Signal Battery) U d on E & M Types II, III, IV (Type IV is not supported on Cisco router/
gateways).
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T/R (Tip/Ring) T / R leads carry audio between the signaling unit and the trunking circuit. On a
two−wire audio operation circuit, this pair carries the full−duplex audio path.
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T1/R1 (Tip−1/Ring−1) U d on four−wire audio operation circuits only. The four−wire
implementation provides parate paths to receive and nd audio signals.
•
E & M Signaling Unit Side and Trunk Circuit Side Compatibility Issues
E & M signaling defines a trunk circuit side and a signaling unit side for each connection similar to the data circuit−terminating equipment (DCE) and data terminal equipment (DTE) reference type. Usually the PBX is the trunk circuit side and the Telco, CO, channel−bank, or Cisco voice enabled pl
atform is the signaling unit side. The Cisco analog E & M interface functions as the signaling unit side and it expects the other side to be a trunk circuit. When you u E & M interface models Type II and Type V, you can connect two signaling unit sides back−to−back by appropriate crossing of the signaling leads. When you u E & M Type I and Type III interfaces, two signaling unit sides cannot be connected back−to−back.
Many PBX brands have E & M analog trunk cards that can operate as either the trunk circuit side or the signaling unit side. Since the Cisco E & M interfaces are fixed as the signaling unit side of the interface, it might be necessary to change the E & M trunk ttings on the PBX to operate as the trunk circuit side. If you u Type I or III E & M, this is the only way the PBX works with the Cisco E & M interface.
Some PBX products (and many key systems) can only operate as the signaling unit side of the E & M interface. This means that they cannot interoperate with the Cisco E & M interface if Type I or Type III is chon. If Type II or Type V E & M is ud, PBX products fixed as "signaling unit" side can still be ud with the Cisco E & M interface via Type II or Type V.
Each E & M signaling type has a unique circuit model and connection diagram. The figures in this document illustrate the different types.
E & M Type I Interface Model
E & M Type I is the original E & M lead signaling arrangement and it is the most common interface type in North America. This table displays the nt signal states for on/off hook signaling.
,,,PBX to Cisco
Router/Gateway Cisco Router/Gateway to
PBX
Type
Lead On−Hook Off−Hook Lead On−Hook Off−Hook 1
M Ground Battery E Open Ground
The router/gateway grounds its E−lead to signal a trunk izure. The PBX applies the battery to its M−lead in order to signal a izure. Cisco router/gateways expect to e off−hook conditions on the M−lead and signal off−hook to the remote device on E−lead.
Note: For the four−wire audio tup, Pin 6 (Tip) and 3 (Ring) on the router transport the audio path from the PBX to the router. Pin 5 (Tip1) and 4 (Ring 1) on the router transport the audio path from the router to the PBX.
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Note: For the four−wire audio tup, Pin 6 (Tip) and 3 (Ring) on the router transport the audio path from the PBX to the router. Pin 5 (Tip1) and 4 (Ring1) on the router transport the audio path from the
router to the PBX.
Things to consider with Type II interfaces include:
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Two signaling unit sides can be connected back−to−back if the appropriate signaling leads are
swapped.
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摄影师头像Six wires are ud for Type II, two−wire audio operation.
Eight wires are ud for Type II, four−wire audio operation.
•
•
Type II us four leads for supervision signaling: E, M, SB, and SG
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During inactivity both the E−lead and M−lead are open
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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 Interface Model
E & M Type III is a partially looped four−wire E & M arrangement with ground isolation. The signaling unit provides both the battery and the ground. This table displays the nt signal states for on/off hook signaling.
The router ns loop current on the M−lead for an inbound izure and grounds its E−lead for an outbound izure. Cisco router/gateways expect to e off−hook conditions on the M−lead and signal off−hook to the remote device on E−lead.
