Busy Lamp Fields (BLF)
The busy lamp field function signals which of your colleagues is currently in a call or available.
Updated over a week ago

Destinations with the "Busy Lamp Field" function send a message to the phone system in addition to the functionality of the standard VoIP destinations. This makes it possible to see below BLF users whether another user is on the phone or receiving an incoming call. With these users, it is also possible to call them directly via a BLF key or to accept calls. If an employee sees that a colleague who has just been called is not at his desk, he can take the call on his phone using his "Monitoring button".


  • Display of a VoIP destination status (busy, free, incoming call)

  • Picking up incoming calls from other VoIP destinations ("Pick up")

  • Internal direct dial-in by pressing the function key

  • Transferring calls to a BLF destination

Quick setup (autoprovisioned end devices):

  • Booking the Premium Package

  • Creating an end device with VoIP destination Type BLF

  • Assigning the BLF keys under IP end device > Function keys/BLF

  • Reconfigure the end device - the BLF keys are now already assigned.

Not possible:

  • BLF keys setup for manually configured end devices in the Placetel customer account

  • Extensive presence features - only the server status of the VoIP destination is shown here

  • Monitoring of standard users

  • Changing a standard user to a BLF user

Important note

We only provide support for Cisco, Snom, and Yealink end devices regarding the Busy Lamp Fields feature & Pickup. These end devices can be configured via the autoprovisioning function.


In order to use the BLF functionality, you first need VoIP destinations with the type BLF. You set the VoIP type directly when you create the employee or the VoIP destination.

If you have booked the Premium Package, you can add a checkmark for the BLF option during the employee setup. The busy lamp fields option can then be used by this employee later on. It is only displayed when the Premium Package has been booked, otherwise you will not see this option.


BLF & Direct Dial

1. Create a BLF VoIP destination under PBX > VoIP Destinations - if you have not already done so. A standard VoIP destination does not work here.

2. Switch to PBX > IP Device and select the end device whose BLF buttons you want to configure.

3. Make sure you provision a BLF VoIP destination on the phone line

4. Switch to the Function Keys/BLF tab and determine which VoIP destination should be stored on which function key.

5. You can also provision direct dialing to the function keys of a phone. Simply enter the external call number that you want to dial when you press the key. If you add a "|" symbol after the call number, you can also still label the function key on the phone. This must be supported by the end device.

6. If you do not want to store a function on a function key, you can also select Empty.

Extension module

For many CISCO phones you can purchase the corresponding extension module in the shop, which provide you with additional feature keys. You can also provision and assign these in the customer account. To do this, also follow steps 1-6, but note that the additional keys are set in the customer account (End Devices > Function Keys/BLF > Extension Unit) under the built-in keys. You may have to open the corresponding menu first.

BLF Pickup groups

Placetel also gives you the possibility to create a BLF pickup group. This group does not ring, it can only be provisioned as a BLF key on a end device. If one or more destinations in the group are called, the corresponding BLF field flashes and the call can be picked up by pressing the button.

If you want all destinations of a pickup group to ring, you must create an additional ring-all group and route it behind a call number.

Pickup monitoring groups only flash when a call from outside goes directly to one of the units or to a ring-all group. For internal calls to a unit in the group or when transferring, the pickup group does not flash.

  1. Switch to Administration > Groups > Create new caller group

  2. Enter a name for the group and select Type in the drop-down menu: Pick-Up Monitoring Group

  3. Select all VoIP destinations which should be part of the group and save the settings

  4. Switch to the relevant end device and configure the pickup group with a free BLF key of the phone

  5. Repeat step 4 for all end devices which should monitor the group. These devices do not have to be part of the group!

Manual setup of BLF keys

Basically you can also configure BLF keys in softphones and non-autoprovisioned end devices. Each end device functions differently. Therefore, we cannot offer general instructions.

The following information may help you with the configuration:

  • Often an account or user is requested for monitoring per BLF key. In most cases, this is the SIP user name that is displayed in your customer account under the corresponding VoIP destination. Sometimes this must be extended by @blf.finotel.com.
    Example: 777d0asmdcp@blf.finotel.com

  • To be able to "pick up" calls, you need a pickup code. For Placetel this is: *822

  • Example for a manual assignment of a BLF key with Snom: sip:SIPKENNUNG@blf.finotel.com;user=phone|*822

  • Please note that other presence features supported by some softphones cannot be used. You will therefore not see when the subscriber changes his presence status in a softphone, but only the status that the VoIP destination has on our server (incoming call, busy or free).

  • A configuration guide for Bria / X-Lite can be found here.


My BLF keys light up permanently or are "stuck on".

  • Dial 2001 from a phone system. This resets the status of the BLF fields.

  • Assign the SIP and RTP ports of your end devices manually as described in this online help article. If necessary, you must forward the corresponding ports in the router.

  • Make sure that an updated firmware is installed on your phone.

Can I turn a BLF user into a standard user or vice versa?

  • No, you must delete the user and create a new one.

On my CISCO phone the last function key is not correctly used.

  • On a CISCO phone, the first function key is always defined as a line key. Therefore, with 4 function keys, you only have 3 keys left for BLF functions. The second hardware key therefore corresponds to the first BLF field in the customer account. The last BLF field cannot be used at the moment.

When pressing on the BLF key, the subscriber is called, but the SIP identifier appears in the display and not the extension number?

  • This behaviour is correct, the SIP user is always called, and not a corresponding extension.

Can I turn a BLF user into a standard user or vice versa?

  • No, both users must have type BLF in order to enable proper monitoring.

Why are standard destinations in the BLF pickup group not monitored correctly?

  • You can select standard destinations, but this has no impact since only BLF destinations can be monitored.

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