Mitel SUPERSET 420 User's Guide download pdf (Page 24)

PBX Integration Board User’s Guide

2.6. In-Band Signaling

PBXs may use a method called in-band signaling to control their station sets.

In-band signals use the same band of frequencies as the audio signal; this is

usually accomplished with touch-tone signals. This method provides a limited

amount of integration because there are no standards and different PBXs provide

varying levels of control. Call progress tones that even similar models send can

vary. This means that applications, even on identical PBXs, have to be tuned with

each installation.

An example of in-band signaling is transferring a call using the flashhook method

There is no data (e.g., caller ID information) passed along when the call is

transferred.

2.7. Out-Of-Band Signaling

Many PBXs use a method called out-of-band signaling to control their station

sets. Out-of-band signals do not use the band of frequencies used by the voice

signals. These PBXs transmit control signals and data that can include

information such as called/calling number ID. Because of its versatility, out-of-

band signaling is the preferred method.

2.8. Read Display Messages

Most PBX station sets have an LCD or LED screen that can display messages.

The type of information that is displayed varies with the PBX manufacturer and

the programming capabilities of the switch. Typical information includes:

calling/ called number ID from within the switch, ANI digits from the CO, hook

state, time and length of call, name assigned to the extension, and message

waiting notification. With a PBX integration board, this information can be easily

passed “unprocessed” to the application. This means that the same data that is

sent to the display is captured by a PBX integration board.

By capturing the same display messages that a phone set receives, an application

can “see” and “record” the display information. This display information (in

ASCII format) is especially useful in CT applications because it enables an

application to know exactly what state the extension connected to the PBX

integration board is in. Applications used with a PBX that provides ANI digits

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Mitel SUPERSET 420 User's Guide Page 24