I'll bet every one of the 17 intelligence agencies have ability to read text messages without a warrant. Using them back to the originator, that's pretty bold and crossing many lines of what you're not supposed to do with that information.

5G mmwaves frequencies only in populated areas, cities. One task of GPS antennas on towers is location. 2nd part of the FCC 911 mandate added LIne Measuring Units, which can give exact location of transmitting tower. So they know which tower the burner phone transmitted from. Also known would be the carrier. The carrier likely VERIZON since they have the most complete 5G system since they were the test bed for the 3GPP Working Group, the international specifications body of the global wireless community.