Open Barres is a free and ad-free application offered by the National Frequency Agency (ANFR) which allows you to obtain:
- the strength of the signal received by your Smartphone from your operator's 2G, 3G, 4G and 5G networks;
- technical information on mobile telephone networks open to the public;
- weekly updated information on the deployment of 5G networks open to the public in mainland France, without the need to use a 5G phone;
- information relating to exposure to radio waves emitted by mobile telephones.
With Open Barres, you can measure and record the strength of the signal received (GSM, UMTS, LTE) by your phone from the network of the operator to which you are connected . The signal value is displayed in dBm in a color code depending on the power received by the phone. You can record power measurements during a trip with additional technical information associated with each measurement (such as celID, MNC, LAC, MCC, U/E/ARFCN, etc.), then download and share all of this data to analyze it or have it analysed. You thus know, for example, the zones where the signal of the network of your operator is strong or, conversely, weak.
 The signal strength received by your mobile phone is measured in dBm. The lower the dBm value, the weaker the signal strength received by your phone. When signal reception is good, the phone reduces its transmission power to the minimum necessary to ensure a good connection, which helps to reduce your exposure to radio waves emitted by your phone.
Open Barres allows you to discover in real time, on a cartographic background, the base stations around you, with the operators who use them and the 2G, 3G, 4G and 5G technologies deployed there. Depending on the density of cell towers, it may be necessary to pan the map around your location or change its scale to see cell towers.
With Open Barres, you can find out the status of 5G deployment by counting and mapping 5G sites that are technically operational or authorized but not technically operational, by operator, by municipality and at the national level, with a detail by band of frequencies. By opening the "5G deployment" function, Open Barres automatically informs you of the status of the 5G deployment of the municipality in which you are located and for the network of the operator to which you are subscribed. You don't need to be using a 5G phone to get this information. 5G deployment status data is updated every weekend.
Open Barres informs you about the SAR values  of your mobile phone by providing you with the values published by its manufacturer. When your phone's SAR values have been checked by the ANFR, you will also see them in Open Barres.
 SAR measures the quantity absorbed locally by your body (head, trunk, limb) when it is exposed to the radio waves through which your telephone communicates with the relay antennas. SAR measurements need to be carried out in the laboratory given the equipment required; they cannot therefore be carried out in real time on your mobile phone.
With Open Barres, you can learn about "good behavior to reduce exposure to radiofrequency waves emitted by mobile phones" published by the Ministry of Health, the Ministry of the Environment, ANSES and the ANFR, and thus adapt your uses of your mobile phone.