There is zero cell service there. For any carrier. There are pay phones. We found we could drive toward west Yellowstone and get cell service without having to leave the park. Or there will be cell service by Canyon or Old Faithful. ( A satellite dish will work for tv reception)

Non existent - there are typically no towers inside national parks and this campground is too far in the interior to pick up an outside signal. I believe the only campground at Yellowstone with ATT service is Mammoth, which gets a faint signal out of Gardiner.

Zero none. You have to drive 10mi into West Yellowstone for service. There is very little signal in all of Yellowstone park.