Tweets coordinate reference system




I’m trying to exploit tweets geolocated ( and see coordinates)
But I need to know what is the coordinate reference system.
I found a topic on the forum where the answer was WGS 84 but I’m not very sure of this because there is no explanaton.
Actually, it seems that the coordinates are in the coordinate reference system of the user which sends the tweet.
So, as I think all smartphone use WGS84, so tweets coordinates would be in WGS84.
In spite of this reasoning, I’d like to be sure and I’ll be very happy if a member a the twitter staff could answer this question.

Even if you don’t know the answer, maybe you could help me by confirm or not that smartphones use WGS84 ( and not WGS84 Web Mercator ( or another CRS.