It could be done multiple ways, you could use something like bluetooth advertising, this is being used more and more. Lots of signs outside advising people to turn on bluetooth etc, it has been used quite a bit with concerts to push out info and offers.
There are other ways too but they aren't classed as legal/ethical. I don't really want to go into that though, google is your friend if you want to learn more
Cell broadcasting is an option but I doubt they would be able to use it for a publicity stunt.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.