Is there cell phone reception at Gerstle campground? Thank you1

Yes. Verizon and ATT only. Brand new Cell tower. 5 bars everywhere.

I got bars in the day use area

There is reception but most of the time it is very weak, maybe one bar, and is very unpredictable. There are certain areas such as the visitor center where you are more likely to get reception but certainly download trail maps at home! 😁