https://www.theverge.com/2018/3/25/17160944/facebook-call-history-sms-data-collection-android

Facebook has been collecting call records and SMS data from Android devices for years. Several Twitter users have reported finding months or years of call history data in their downloadable Facebook data file. A number of Facebook users have been spooked by the recent Cambridge Analytica privacy scandal, prompting them to download all the data that Facebook stores on their account. The results have been alarming for some.

“Oh wow my deleted Facebook Zip file contains info on every single phone cellphone call and text I made for about a year,” says ‏Twitter user Mat Johnson. Another, Dylan McKay, says “somehow it has my entire call history with my partner’s mum.” Others have found a similar pattern where it appears close contacts, like family members, are the only ones tracked in Facebook’s call records.