The data collection was uncovered in an investigation by Quartz magazine, and Google confirmed that phones collect the addresses of nearby phone towers. The data on cell towers is sent to the system that manages communications and push notification.
Google has only said that it was done to "further improve the speed and performance of message delivery".
The company claims that the data was never incorporated into its systems and was immediately discarded.
"We can confirm that the ActivityRecognition algorithms work offline, but do not know if any of that data is sent to Google servers (they probably do not need it, they already have access to our geolocation, again through the Play services)".
A spokesperson for Google said the data was never stored and promised to end the practice. But recent report gave me a shock because I always thought that turning location off doesn't give my location data to Google.
This marks the second time in recent months the search giant has been caught collecting user data under questionable circumstances.More news: Chelsea quartet out of Qarabag clash
The revelation comes as Google and other internet companies are under fire from lawmakers and regulators, including for the extent to which they vacuum up data about users.
Your Android smartphone could be tracking your every move, even when location services are switched off, it has emerged.
It was Quartz that first noticed the unusual location tracking behavior.
For example, if you're on the north side of a park and connected to Tower A, your Android phone will send a Cell ID code to it that essentially says "Yes, route messages through Tower A for the quickest and most delivery". You would have to use triangulation of multiple towers in order to really get a specific location from the information. The company has an app as well as a website for accessing the Google Calendar. Most concerning is that the info was sent from smartphones that have location services turned off.
However, a source reportedly told Quartz that Google added in the collection of cell tower addresses as an improvement for its Firebase Cloud Messaging.
Although the data sent is encrypted, a third party could make use of it if the handset has been infected with spyware, malware or other hacking tools.