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Busy Lamp Field (BLF)

Updated: 16/05/2019 13:51

Busy Lamp Field (BLF) displays the status of other extensions on your phone's display, such as IdleRinging, or On a Call.

  • Included with your Vonage service.
  • Available for extensions used in Call Groups, Paging Groups, and Call Queues. 
  • Does not affect the behavior of  On-Demand Call Recording, Company Call Recording, or Call Monitoring features.
  • Not supported by Virtual Extensions, Mobile App, Desktop App, and Softphones. 

NOTE: Shared Line Appearance cannot be used when BLF is set up. If you want to switch from BLF to SLA, you must first remove BLF and then add Shared Line Appearance.

Only the Super User and Administrators can set up BLF.

Supported Phones and Expansion Modules
Expansion modules can increase the number of extensions monitored, if applicable. See Expansion Modules (Sidecars) for details. Phone models that support BLF include the following:

Phone Model 

Compatible Expansion Module

Polycom VVX 150
Polycom VVX 250
Polycom VVX 301
Polycom VVX 311
Polycom VVX 350
Polycom VVX 401
Polycom VVX 411
Polycom VVX 450
Polycom VVX 501
Polycom VVX 601 
  • Polycom VVX Expansion Module
  • Polycom VVX Colour Expansion Module 
Set Up Busy Lamp Field

To enable monitoring of an extension:

  1. Sign in to the Admin Portal.
  2. Click Phone System, then click Line Appearance.
  3. Click Add Line Appearance, then select Busy Lamp Field when setting options:
    ExtensionSelect the extension you want to use with BLF from the drop-down list.
    Line Appearance Options
    Shared Line AppearanceMonitors other extensions and lets you answer or place calls from those extensions.

    See Shared Line Appearance for details.
    Busy Lamp FieldMonitors the status of other extensions only.
    Select DeviceSelect the phone on your extension you want to use with BLF.
    Display Line Appearance
    Base Unit Only, or Base Unit and Expansion ModuleExtensions display on your phone until all slots are used and then your expansion module displays the remaining.
    Expansion Module OnlyExtensions only display on your expansion module.
    Monitor ExtensionsSelect extensions from the menu that you want to monitor on your phone's display. After adding extensions, click and drag each one in the order you want them to display.
  4. Click Save.
  5. Unplug the power cord from your phone and wait 10 seconds before plugging it back in. Your phone and/or expansion module now displays the extensions you chose to monitor.

    NOTE: You can monitor up to 100 extensions, however, the number of extensions your phone can monitor varies.
Manage Busy Lamp Field

You can edit or remove an existing BLF using the following steps:

  1. Sign in to the Admin Portal.
  2. Click Phone System, then click Line Appearance.
  3. Hover over the extension you want to manage and select an option:
    RemoveWhen you remove BLF, the extensions you chose to monitor no longer display on your phone's screen.
    1. Click the Trash icon to remove BLF.
    2. Unplug the power cord from your phone and wait 10 seconds before plugging it back in.
    EditClick the Pencil icon to edit settings.
Busy Lamp Field Colour Indicators by Phone Make 

Line appearance buttons on the phone light up according to manufacturer settings.

Polycom VVX BLF Colours:

Solid GreenActive call in progress
Flashing GreenCall on hold
Fast Flashing GreenIncoming Call
Solid RedMonitored extension is placing a call or is on an active call
Troubleshooting Issues
Extensions Not Displaying Correctly

Your phone must be auto-provisioned for line appearance to work. See applicable article:

Status/Presence Not DIsplaying CorrectlyDisable SIP ALG on your router.

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