Getting the flight number

Hello,

I am sorry if this question was already answered. I am working on an academic project and I want extract the flight number along with vectors states. While exploring the map, the commercial flight number is listed when selecting a airplane. For exemple, the flight AY216 with callsign FIN216 in the image, but I can't find a method to obtain it from the API.
I found in this article  from the FAQ (question 13)  Crowdsourced air traffic data from the OpenSky Network 2019–2020 that shows a Opensky dataset with commercial flight number included. If it's not possible to extract from the API, is there another way to find it ?

Thanks.