Extension Buttons and Status Lights: Understanding BLF

Busy Lamp Field (BLF) shows the status of a configured extension or line on a button or screen indicator. It helps you see whether that line is idle, ringing or busy before deciding how to handle a call.

Read the label before the light

Confirm which extension the key monitors. An indicator describes a line state, not whether the person is at their desk or willing to take a call. An idle line is not a guarantee of availability.

Do not use one color chart for every phone. Colors, icons and flashing patterns vary across Yealink, Polycom and Cisco models and can depend on configuration. Use the meaning confirmed for your phone. A blank or unknown indicator should not be treated as proof that the person is free.

Know what pressing the button will do

1. Identify the key’s purpose. Ask whether it monitors a person, dials a number, picks up a ringing call or accesses Park.
2. Check your current call state. A key can behave differently while idle and during an active call. On some configurations, pressing an extension key during a call can transfer the caller.
3. Use only the action configured for that key. If pickup is enabled, use it only for ringing calls you are authorized to answer. Otherwise follow the separate Call Pickup guide.

BLF, speed dial and Park are not the same

• BLF: provides monitored line status when configured.
• Speed dial: calls a saved destination; a shortcut alone does not guarantee status monitoring.
• Park: refers to a shared waiting location, not necessarily a teammate’s extension. See Call Park.

Wrong label or status that does not update?

Report your phone model, your extension and the label or extension being monitored to Zonitel support. Explain what the other line was doing when you noticed the mismatch. Do not overwrite managed keys, change account settings or assume a status key grants permission to listen to an active call.