Correct me if I'm wrong, but there's got to be at least one app on the person's phone that's reporting GPS info that is feeding information to the marketing company. Is the name of the app(s) mentioned?
Usually this is done in cahoots with the carrier - you’re typically buying the advertising from them. At least, that’s how it is here in Canada.
i doubt it. do carriers really sell advertising directly to their clients? ie. does the company have a advertising division where you can spam SMS to their clients within a certain radius?
Actually, yes. I was pitched by ad reps from the largest carrier - they claimed to be able to send an SMS when one of their customers enters a geofenced area.
In a population centre you can probably map to 50m accuracy or less based on the wifi networks one can see - can apps report back the specific networks? Isn't that kinda how Google's enhanced "location services" works?
Facebook? Zip code is a targeting option in FB ads, unless I'm mistaken.