"The data is gathered from smartphone apps in which the users have granted permission for location tracking. Though anonymized, a recent report from The New York Times showed how easy it is to connect this data to identities of people in the real world."
"The report says that the DHS agencies have been buying the location data from a company called Venntel, which also declined to comment. But the fact that the government is purchasing this data from a commercial provider — just like any company could — makes it easy to circumvent court-set limitations for this type of surveillance."
https://mashable.com/article/dhs-tracking-cellphone-location/
Does that mean Venntel sells tracking information in real time? That should probably be illegal.
>real time
According to the WSJ, no.
"Venntel buys it first from private marketing companies who buy it from apps which have been granted access to a person's location services on their phone. Then, it sells it on - mostly to advertisers - but also branches of government."