From app blogs Methodology explains how they collect data
Crowd Sourcing (already pointed in comments)
Monitoring users who installed app continuously
So, the accuracy pretty much depends on how many people use the app with GPS on
- Data Analytics
Also see Cell towers/wifi routers not located correctly which is dated but relevant
This app was recently launched in India and I noticed this
Cell towers are very well mapped of a provider, though, in my area tower density is low ( likely because theyprovider made it open source as a part of publicity )
Cell towers are not well mapped, for another provider, though the tower density is much higher
Not a very dependable app , IMO