Privacy respecting video conferencing

Frequently Asked Questions (FAQ)

Here you can find frequently asked questions (short: FAQ) and corresponding answers to our project.

How can I make video conferences with Senfcall?

With Senfcall private individuals can easily and spontaneously start video conferences. This can be done via the button "Start meeting" in the navigation bar. After clicking on it, you must first agree to the privacy policy (on your first visit). Afterwards, a name and optionally a password for the conference can be selected via the input fields. We recommend the use of a password.

In the next step the echo test can be used if you want to participate with a microphone. If not, you can also participate in the conference by listening only. After entering the conference, the camera, microphone (and for the presenters also the screen transmission) can be switched on and off using the blue function buttons at the bottom right.

The person who creates the conference has moderation rights. These can be used to mute participants, turn individual participants into presenters and assign moderation rights to other participants. This can be done via the menu which can be opened by clicking on the arrow next to the name of each participant. When a moderator enters the conference, important information on how to operate the conference is displayed in the information area of the chat. For example, an automatically generated password is displayed, which allows participants to join the conference instead of the password they chose themselves. If this password is used to dial into the conference, these participants become moderators as soon as they enter the conference.

If the conference is ended manually, or the last person leaves the conference room, the room including the uploaded presentation, chat and shared notes will be deleted from our servers after a short delay.

How can I create permanent rooms?

With an account at Senfcall, up to 10 rooms can be created, which are always accessible using the same link and offer additional functionality (e.g. waiting room). You will be able to create and manage these rooms at as soon as you are logged in. Our FAQ also explains how to get a Senfcall account.

How can I register an account?

Senfcall accounts are free of charge. To sign up for an account fill in the registration form of our lecture system. Senfcall will send a confirmation mail to you, including a confirmation link. After clicking this link you can log in to your activated account.

Protect video conferences from disruptions

Uninvited guests can disrupt video conferences if the BigBlueButtonTM protection mechanisms are not used for this purpose. In our videotutorial on protection mechanisms (only available in German for now) we explain how to do that. For many measures, a permanent-room is necessary or helpful.

How do I join a conference by phone?

As soon as there is one person connected to the meeting with active microphone, other users can join via dial-in connection. At the start of a meeting, the moderators will receive the corresponding phone number and the conference PIN in the welcome message in the chat. Additionally you can access the dial-in information before starting the echo-test, when joining the meeting and clicking on the small text "Join by phone" below the microphone and headphone buttons for joining in speaking or listening mode. Please note that the conference PIN must be confirmed using the hash key (#). For technical reasons, it is not possible for now to configure the PIN and the phone number in advance.
The costs you incur for telephone dial-in depend on your telephone tariff for a connection to the German fixed network.

Why is Senfcall free?

Senfcall is donation funded and run mostly by volunteers. We are committed students who, in the course of the Corona Pandemic, were confronted with the fact that they had to do their studies from home.
We have found out that there are only a few solutions that are compliant with data protection and at the same time free of charge for us students.
The desire arose for a platform that meets both requirements and works reliably.
That is our motivation to run this project free of charge.

Why am I getting a warning that I should use a different browser?

In order for video transmission in the browser to be possible at all, open standards (keyword "WebRTC") have been created, which browser manufacturers must support.
But with some of them this does not work quite as well, the browser has not been updated for a long time or the development of the browser has been stopped.
Because the development team behind BigBlueButton™ has limited financial and human resources, the developers have limited themselves to the most widely used current browsers to test BigBlueButton. This should not prevent you from using Senfcall despite the warning.
However, it is possible that due to the outdated technology, problems may occur that we cannot fix. For privacy reasons we recommend Firefox. On OSX, the developers recommend the Safari browser. The latest browser versions of Chrome/Chromium and Edge are also supported.

What data protection measures does Senfcall take?

Meetings are not recorded.
Uploaded presentations will be deleted after the meeting ends.
The names of the meeting participants and the room passwords are not saved beyond the end of the meeting.
The data traffic from and to our servers uses transport encryption.
The software we use, "BigBlueButton", in its standard configuration, sometimes integrates external resources, such as videos from other websites and fonts from "Google Fonts".
We have deactivated the corresponding functions.
However, we do store some data, such as the browser used, in our log files in order to be able to trace technical problems in the event of an error.
Details can be found in our privacy policy. We have made every effort to formulate it in a way that is generally understandable.

What do I have to consider for big events at Senfcall?

In the meantime we could gain some experience with big events that were run via Senfcall. We have put together a few tips to ensure that future big events run smoothly:

  • Meetings with about 250 participants have worked well so far. However, we cannot guarantee that meetings with significantly more than 250 people will go just as well.
  • As few camera transmissions as possible should be switched on. For web seminars it is best to use only the camera of the person giving the presentation.
  • If a presentation is to be shown, it is worth uploading it on the plus in the bottom right corner. Transmitting the screen requires disproportionately more bandwidth and places a heavy load on both the server and the participants' computers.
  • It may also be worthwhile to delete the chat history from time to time (on the three dots above the chat). This is because the chat history is sometimes responsible for putting a heavy load on the processor of the participating computers.
  • Excessive painting (many people at the same time) on the slides can put a strain on the server. So please try to avoid this. The last two points are idiosyncrasies of BigBlueButton. However, both have already been fixed and will not occur in a future version. If there are still any questions about your big event, don't hesitate to contact us via Mail.

Can I use Senfcall for my organisation/educational institution/company?

We do offer data processing agreements and API access for German non-profit organizations. Please see the corresponding page in German for more information.

Does Senfcall offer company accounts or data processing agreements?

We do offer data processing agreements for German non-profits (see above). We do not offer commercial hosting, as we run Senfcall on a voluntary basis as a project of Computerwerk Darmstadt e.V.. There are a number of companies offering hosting and support for the software "BigBlueButton" used by Senfcall. Here is a selection of commercial providers for BigBlueButton hosting in Germany, without any claim to completeness:

If you have an IT department with a suitable server infrastructure and network connection, you can also operate BigBlueButton yourself. IT administrators can find the relevant documentation at

A number of international companies also offer consulting services for BigBlueButton and software customisation. Information on this can be found on the BigBlueButton partner page.

Do you have a question that is not yet here?

Unfortunately, we can only offer very limited support via email due. If you encounter issues please contact the creator of your meeting first or search for help in the internet with the keyword "BigBlueButton". We will read most of the emails but won't be able to answer them most of the time. You can report bugs still to

Video tutorials

Create spontaneous meeting room (German only)

Protect video conferences from disruptions (German only)