Yealink BLF Configuration
Set up Busy Lamp Field to monitor extensions and streamline call handling
What is BLF?
Busy Lamp Field (BLF) is a feature that lets you monitor the status of other extensions directly from your phone. LED lights next to programmed buttons show whether colleagues are available, busy, or their phone is ringing.
Key Benefits:
- ✓ See colleague availability at a glance
- ✓ Transfer calls with one button press
- ✓ Pick up ringing calls for other extensions
- ✓ Speed dial frequently contacted extensions
Before You Begin
This guide assumes you have already added device extensions in your Siptalk portal.
Required Information: You only need the Extension Alias (4-digit number) of each extension you want to monitor.
Step 1: Identify Extensions to Monitor
Example Scenario:
We'll configure BLF on a phone connected to extension 1001 to monitor extension 1002.
First, locate the extensions in your portal to confirm the extension numbers:
Click image to enlarge
Step 2: Configure Line Keys
Accessing the Web Interface:
- 1. Find your phone's IP: MENU > STATUS > IPv4
- 2. Browse to the IP address from a computer on the same network
- 3. Login (default: admin/admin)
- 4. Navigate to Dsskey > Line Key
Click image to enlarge
Configuration Explanation:
Line Key 1 (Your Extension)
This is already configured as your phone's own extension (1001 in our example)
Line Key 2 (BLF Monitor)
Configure this to monitor another extension:
After entering the settings, click Confirm to save the changes.
Understanding BLF LED Indicators
Green Light
Extension is idle and available. You can transfer calls or dial this extension.
Solid Red Light
Extension is busy on a call. Transfers will go to voicemail if configured.
Blinking Red Light
Extension is ringing. Press the BLF key to pick up the call.
No Light
Extension is offline or unregistered.
Using BLF Features
Quick Transfer
While on a call, press a green BLF button to instantly transfer the call to that extension.
Directed Call Pickup
When you see a blinking red BLF light, press that button to answer the call ringing at that extension.
Speed Dial
When not on a call, press any BLF button to instantly dial that extension.
Status Monitoring
See at a glance who's available before transferring calls or walking to their desk.
Best Practices
- • Use descriptive labels (e.g., "Reception", "Manager", "Warehouse") instead of just numbers
- • Configure BLF for frequently contacted colleagues or important extensions
- • Consider using expansion modules for phones that need to monitor many extensions
- • Group related extensions together (e.g., all sales team members in sequence)
- • Document your BLF layout for consistency across similar phones
Model-Specific Information
Standard Desk Phones
- • T46S/G: 10 line keys
- • T48S/G: 16 line keys
- • T54W: 10 line keys + USB expansion
- • T57W: 16 line keys + USB expansion
With Expansion Modules
- • EXP50: Adds 60 buttons (20 x 3 pages)
- • EXP40: Adds 40 buttons (20 x 2 pages)
- • Up to 3 modules can be chained
Note: Older models may have slightly different menu layouts, but the configuration fields remain the same.
Troubleshooting
BLF lights not working
Ensure both phones are registered and online. Check that the extension number is correct.
Can't pick up calls
Directed call pickup may need to be enabled in your PBX settings. Contact support if needed.
Wrong extension monitored
Double-check the Value field contains only the 4-digit extension number, no prefixes.
Related Guides
Frequently Asked Questions
What is BLF on a Yealink phone?
BLF (Busy Lamp Field) allows you to monitor the status of other extensions on your phone. LED lights show if extensions are idle (green), ringing (blinking red), or busy (solid red), enabling quick transfers and visibility of team availability.
What information do I need to configure BLF?
You only need the Extension Alias (the 4-digit extension number) of the extension you want to monitor. This is found in your Siptalk portal extension list.
How many BLF keys can I configure?
The number depends on your Yealink model. T46S has 10 line keys, T48S has 16, and T54W/T57W have up to 60 with expansion modules. Each can be configured as a BLF key.
Can I transfer calls using BLF keys?
Yes! While on a call, simply press the BLF key of an available extension (green light) to transfer the call. This makes call handling much faster than dialing extension numbers.
What do the different LED colors mean?
Green = extension is idle/available, Blinking red = extension is ringing, Solid red = extension is busy on a call, Off/unlit = extension is offline or unregistered.
Can I pick up calls for monitored extensions?
Yes, when a monitored extension is ringing (blinking red), you can press the BLF key to pick up the call directly, known as directed call pickup.