> For the complete documentation index, see [llms.txt](https://help.sipgate.de/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.sipgate.de/cloud-telefonanlage/en/using-sipgate/telefonie/was-ist-das-besetztlampenfeld-blf.md).

# What is the busy lamp field (BLF)?

If you want to display the **telephone status** of colleagues on your own phone, the busy lamp field (BLF) is the feature of your choice. It is included in the business L and XL plans. To use the function, the users you have created must have an **internal extension** assigned. Once correctly configured on the device, the BLF shows these three statuses:

* **available**: colleagues are not on a call, the busy lamp is off.
* **busy**: colleagues are speaking, the busy lamp stays on continuously.
* **ringing**: colleagues are currently being called, the busy lamp flashes.

The BLF configurations differ from model to model.

Instructions for this can be found on the manufacturers' websites and in the documentation that came with your phone.

We have tested BLF configuration on a whole range of phone models; here you will find the [configuration instructions for Snom,](https://help.sipgate.de/hc/de/articles/4408426635921) the [configuration instructions for Gigaset](https://help.sipgate.de/hc/de/articles/4408434099217), the [configuration instructions for Yealink,](https://help.sipgate.de/hc/de/articles/4408427192081-BLF-Konfiguration-f%C3%BCr-Yealink) the [configuration instructions for Tiptel](https://help.sipgate.de/hc/de/articles/4408427390481-BLF-Konfiguration-f%C3%BCr-Tiptel), the [configuration instructions for Grandstream.](https://help.sipgate.de/hc/de/articles/4408427518097-BLF-Konfiguration-f%C3%BCr-Grandstream)

As an alternative to BLF, in your sipgate account you will find under **My Telephony** the [**presence display**](https://help.sipgate.de/hc/de/articles/4408234555025).\
This shows you which users are currently available.

If a user is on a call, the corresponding tile with the internal extension is shown in red.

{% hint style="warning" %}
**Important:** All users must be assigned a **internal extension** .
{% endhint %}


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