Jumbo Rock campground is an excellent area of Joshua tree national Park. The camping is rustic with no running water, but the pit toilets are fairly plentiful for the number of campsites. Nice high-desert camping overall...it does get quite cold at night in the winter. There is absolutely zero cellular signal in the vast majority of the park...you can however get signal on the top of Ryan mountain hike (about 45-60 mins for most people)