Seize a Trunk to Call Out by BLF Key

This topic describes how to configure a BLF key on your IP phone via Auto Provisioning to monitor the PBX trunk, and press the BLF key to quickly place an outbound call through the monitored trunk.


  • If you want to seize a trunk to call out by BLF key, make sure the extension assigned to the provisioned phone has the permission to use the monitored trunk for outbound calls.


Step1. Set up a function key for trunk monitoring

  1. Log in to PBX web portal, go to Extension and Trunk > Extension, edit the extension that is assigned to the phone.
  2. Click the Function Keys tab.
  3. Configure a function key to monitor the status of a trunk.

    The following figure shows a configuration example of monitoring the trunk peer-trunk-66.41.

    • Type: Select BLF.
    • Value: Enter the name of the trunk to be monitored. In this example, enter peer-trunk-66.41.
    • Label: Optional. Enter a value, which will be displayed on the phone screen.
  4. Click Save.

Step2. Apply the configuration to IP phone

  1. Go to Auto Provisioning > Phones, click beside the desired phone.

    The system prompts you whether to reprovision the phone.

  2. In the pop-up window, click OK.


  • The BLF key shows the real-time status of the monitored trunk:
    • Green BLF LED: The trunk is being monitored, and the status is idle.
    • Red BLF LED: The trunk is busy.
    • BLF LED off: The BLF key configuration failed.
  • Press the BLF key to seize the trunk, you will get a dial tone, then dial the number that you want to call.