E&M Voice Subscriber Line; E&M Interface; Start Mode - 3Com MSR 50 Series Configuration Manual

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HAPTER OICE
E&M Voice Subscriber
Line
E&M Interface

Start Mode

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UBSCRIBER INE ONFIGURATION
3 Use the vi-card busy-tone-detect command in voice view to start the detection.
To seize the busy tone signal sent by PBX B, you are recommended to run the
above command 2 seconds after on-hook.
4 (The console terminal displays "Begin to autodetect busy-tone, it will take about
12 seconds, please wait...", which indicates that the busy tone detection is in
progress. After the detection, the terminal displays "Auto-detect busy-tone
succeeded!", which indicates that the detection succeeded.) Use the save
command to save the detected busy tone parameters.
5 Repeat step 2 to verify whether the automatic busy tone detection succeeded. If
succeeded, Telephone A will automatically be disconnected and Telephone B will
hear a "Clatter" sound after PBX B plays busy tones to Router A for 4 seconds.
An ear & mouth or receive & transmit (E&M) interface uses an RJ-48 telephone
cable to connect a PBX. The PBX sends signals on the M (M represents mouth) line
and receives signals on the E (E represents ear) line. Viewed from a voice router,
the router receives M signals from the PBX and sends E signals to the PBX. The
device with an E&M interface can be connected to another device with the same
interface.
When analog E&M is applied in VoIP communication, 2 or 4 voice wires can be
used. Besides, there are 2 or 4 signaling wires. Therefore, 4-wire analog E&M
actually has 6 wires. The 2-wire mode provides full duplex voice transmission and
voice is transmitted in two directions on the two wires. The 4-wire mode is
equivalent to the simplex mode and every two wires are responsible for the voice
transmission in one direction.
An E&M interface supports E&M signaling and divides each voice connection into
trunk circuit side and signaling unit side (similar to DCE and DTE).
An E&M interface provides on-hook/off-hook signals and minimizes the
interference. Because an E&M interface does not provide any dial tone, one of the
following three signaling technologies is used to start dialing:
Immediate start: In this mode, the caller picks up the phone, and some time
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later, the dialed number is sent to the called side. During this period, whether
the called side has been ready for receiving the called number is not checked.
After the called information is received, the callee can pick up the phone to
answer the call.
Figure 652 Immediate start mode
Pick up the phone, requesting for service Pick up the phone, requesting for service
Send the called number Send the called number Send the called number Send the called number
Calling Calling Calling Calling
side (E/M) side (E/M) side (E/M) side (E/M)
Called Called Called Called
side (M/E) side (M/E)
Hang up
Conversation Conversation Conversation Conversation
Conversation Conversation Conversation Conversation
Hang up
Pick up the phone to answer Pick up the phone to answer