Citel Portico TVA Series, Installation And Configuration Manual

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Document Number: G-SIP3D-RUC Version: BB
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Busy Lamp Field (BLF) Overview
A BLF button displays the state of a resource, often another extension, but lines and park locations
are examples of other resources that can be monitored. A BLF button can take different actions
when it is pressed, depending on the state of the monitored extension or other resource. e.g. if a
monitored extension is idle then pressing the BLF button would normally call that extension.
If a monitored extension is ringing then pressing the BLF button might pick up the call.
Normally Idle is shown by the indicator being off and Busy is shown by the indicator being on
continuously Ringing and Held are shown by the indicator either flashing or changing colour,
depending on the phone type.
The TVA relies on notifications from the SIP PBX to tell it the state of the monitored resource (even if
the resource being monitored is another extension connected to the same TVA). This means that
the information available can vary depending on the PBX type. e.g. in some cases a held extension
may just be displayed as busy.
For specific details of Softswitch configuration, please refer to your Softswitch in the SoftSwitch
Integration Guide.
Table 12
shows the mapping between dialog and BLF states.
Dialog State BLF State
None or Terminated Idle
Early Ringing
Confirmed, no local hold Active
Confirmed, local hold Held
Table 12: BLF State Mapping
BLF monitors the status (Idle, Ringing or Active) of extensions on the IP
phone.
BLF State Button Action
Idle Speed dial or one-touch transfer
*1
Ringing Directed call pickup
Active Speed dial
*2
Held As for ‘Active’
Table 13: BLF States
*1: This allows a call to be a) placed if there is no call currently active or b)
transferred if there is a call currently active.
*2: Some application servers, e.g. Asterisk, show the status of a logged out agent as being Active.
Using speed dial for active targets allows an agent to use a single BLF button to monitor their
status and perform log-in / log-out procedures.
A button without an indicator can be configured as a BLF. In this case the state of the monitored
resource cannot be displayed, but otherwise the button behaves the same.