No idea about Gaia.
As for coverage, (Like Wandering Jim says) wherever you have line-of-sight with Lone Pine, you should have some signal.
In my experience (I use Verizon) the areas you can get service on the Mount Whitney Main Trail (MWMT) are as follows:
- N. Fork Lone Pine Creek to TH.
- The windows between the MWMT-JMT junction and the summit.
- The eastern edge of the summit.
The Mountaineer's Route has better cell reception:
- N. Fork of Lone Pine Creek between the MWMT and LBSL.
- Spotty coverage at UBSL.
- Mountaineers chute proper.
- The eastern edge of the summit.
I travel solo a lot, I give a detailed itinerary and carry an emergency PLB. However, when I can, I check my phone periodically to text my emergency contacts updates. As such I've tested it on Whitney a few times.
