
I'm unable to cross post so I linked directly. It's a link to a technical community but here's the gist since we frequently get questions about cell service. This is the most comprehensive and accurate update for cell service in the region.
- Verizon now has 5 towers in the area (Lajitas, Terlingua, Chisos Basin, Panther Junction, and a site by the north entrance
- T-Mobile has 2 towers (Terlingua ghost town and Study Butte) but in certain parts of the park over by the Santa Elena Canyon and Sotol Outlook you'll get all three
AT&T used to have 5 towers, but recently Chisos Basin became a VZ only site so they only have 4. Lajitas, Terlingua, Panther Junction, North side of the park.
If you check cellmapper.com you can see the signal trails marked for the main park roads, the basin, the visitor centers, and even the Lajitas golf course.