Ear & Mouth (E&M) Trunk - Mitel SX-200 EL Technician's Handbook

Troubleshooting and Repair
Test/Verify (DID)
Verify the far-end circuits by the use of a standard telephone for
outgoing calls.
Verify the near-end circuits by connecting to known working DID/Loop
circuits.
Verify that appropriate voltages are present on Tip-Ring in each call
state.
During off-hook condition, 20-25 mA should be drawn from the far-end.
Ear & Mouth (E&M) Trunk
You use the E&M trunk in Tie Trunk applications. The E&M trunks
support all the signaling information.
The Tip-Ring is used in a 2-wire operation shown in
Figure 12 - E&M Trunk - Type I (2-wire) on page 78.
Type 1 may be used in a 2-or 4-wire operation.
The Tip-Ring and Tip Rx-Ring Rx is used in a 4-wire operation shown
in Figure 13 - E&M Trunk - Type V (4-wire) on page 79.
Type I
Type 1 is used in applications when a telephone company is providing
a transmission path between PBXs. The E&M circuits connect to
Telco-provided Signaling circuits, which prepare the E&M signals for
long distance use.
Each end is identical to the other; all required voltage translation is
provided by the cable carrier.
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