>>524877You're thinking "AGPS". Uses cell network for location, ±300m usually. Not very accurate.
Phones that have a standalone GPS receiver will use that for precision location.
AGPS will pump in almanac/ephemeris data to accelerate GPS lock, and provide some additional location data in areas with poor GPS coverage or interference.
Using only GPS, a cold-start (no time, no location info, no constellation info) the unit will take a little under 15 minutes to get all the info it needs to figure out where on the planet it is.
From a cold-start with AGPS, it can grab a rough position along with most of that GPS information from the network and then lock into satellites for an accurate fix in 20-30 seconds, instead of minutes.
A cold-start with no network (like in airplane mode) can still take 12-15 minutes. Usually much less if it's got valid almanac data (warm-start).
Phones without standalone GPS receivers can only use the cellular network for position, usually just enough to meet E911 requirements.
>tfw I do this shit professionally>pic related, satellite constellation on my desk 