It certainly does. Pure inertial guidance with smartphone sensors is garbage. I must say I'm a bit startled by how many people evidently think that GPS is an internet service...
If I had to guess, these conflations of cell service with GPS are a product of misleading UX created by Google. OSMAnd makes the nature of GPS clear, displaying a count of satellites it's managed to hear. Enough satellites to get a location good enough for car navigation almost always takes less than a minute.