[antman]

Two disclaimers: Worked telco, I am in Europe and that data is erased afterwards due to GDPR.

So in the telco in the old days one could use bayesian and accross different days data and pretty accurately know where people are. And it wasn't that useful. Identifying through combination of phone, phone contract, landline, wifi over landline which people were in the same household woukd be useful apparently easier but in reality a total mess in terms of edge cases.