Cell Broadcast (CB)

The public authorities choose the warning channels according to the impact and seriousness of the event that needs to be warned or informed about. Cell Broadcast (CB), for example is used when the event in question is likely to present a significant or imminent danger to the population and immediate action is expected from them.

The triggering of warning and information messages to the population via location-based SMS sends a request to the mobile network operators to transmit the messages entered in the platform by the various public authorities. The mobile network operators then transmit these messages to the population, without any modification, via their own equipment. All mobile devices that are compatible with cellular broadcasting and that are in the area to be warned at the time the message transmission is triggered are targeted.

Yes. Any person in the area to be warned who is connected to a mobile phone relay antenna operated by a Luxembourg mobile network operator at the time the message is sent, will normally receive the warning and information message sent by Cell Broadcast, supposing the mobile device is up to date and operates under a version compatible with the reception of Cell Broadcast (CB) messages by the “LU-Alert” system. See the answer to the question “What types of mobile devices can Cell Broadcast (CB) warning and information messages be received on”).

Mobile network operators transmit the warning/information message by Cell Broadcast (CB) via their equipment to any person in the area to be warned, who is connected to a mobile phone relay antenna of a Luxembourg mobile network operator at the time the message is sent. There are several reasons why a Cell Broadcast (CB) may not have been received:

• If you were near a border, it is possible that your mobile device was connected to a mobile phone relay antenna in the neighbouring country, even if you were physically in the targeted area;
• It is possible that your mobile device was connected to a relay antenna in a neighbouring area that wasn’t targeted, even if you were physically in the targeted area. Several factors determine which mobile phone relay antenna the mobile device is connected to. The warning and information system is dependent on these factors and cannot influence them;
• When the Cell Broadcast (CB) was sent , your mobile device was switched off or in "airplane" mode;
• When the Cell Broadcast (CB) was sent, your mobile device was not connected to a network (weak network in certain regions, buildings, cellars, underground parking, etc.);
• You were not in the targeted area or you were abroad at the time of the alert.

In principle, the reception of Cell Broadcast (CB) messages is instantaneous, there is no delay between the sending of the message by the mobile network operators and its reception by the user.

Once the message transmitted via Cell Broadcast (CB) is viewed, it will disappear from the screen of your mobile device. All transmitted messages can be viewed on the www.lu-alert.lu website.

The Android operator saves the messages in the history of the wireless emergency alerts menu. For mobile devices running iOS, the message can be found in the notification center as long as they have not been deleted.