I downloaded offline maps to Google, for my phone and used that... I have both Verizon and AT&T and can vouch for the crappy cell coverage there.. While I was there, I found Verizon coverage to be much worse than AT&T. West gate had plenty of cell coverage until about halfway to the 4-way stop inside the park... There were a couple places inside the park where I had signal along the river, when my kids were playing.
I drove up from the South Entrance from Teton. I had no cell signal until I got to the intersection where Grand Village was... When I got there, both my AT&T and Verizon Phones had signal, and I started getting a barrage of text messages from our friends we were meeting up with.. I had AT&T signal when we were at Mammoth, as we were stopped along the road to relax in the river. My main issue with Verizon, is that even tho my Verizon phone had signal, it was never able to establish a data connection inside the park, whereas my AT&T phone was able to... When we were at the West Gate, my AT&T phone was able to pull down around 90mbps, but my Verizon phone was getting dial up speeds...
Yeah, I measured upload too... With AT&T at the westgate I was getting 20mbps upload. With verizon I was getting around 1mbps when I was in town, and near 0 everywhere else. When it had signal inside the park, I could only make calls and send texts. I couldn't use data. Whereas AT&T, when it had signal inside the park, everything worked.
Yes, I noticed this issue inside some underground parking. I remember noticing a slash like this: " / " on top of the Network icon, on the top right.
I didn't pay attention to my tesla in a tunnel, but I know my other cars it continues to track inside tunnels, probably because it knows the vehicle velocity and direction. Likewise, I've used it in my other cars inside a parking structure where there was no GPS, but the car rememebred where it was last, and tried to track while driving inside the structure using speed/compass.
