Believe it or not, but in most cities the main form of propagation is actually reflection.
Metal sheets can be great reflectors, but even plain old walls will reflect signals.
In cities you are actually very unlikely to have a line-of-sight signal and most communication will be by reflected and refracted signals.
Mobile networks overwhelmingly use cross-polarized (X-pol) antennas which can allow to detect reflections, however, it is quite impractical.
This all changes with beamforming in 5G where reflections are actively used for beam-steering, and 5G base-stations will actively try to reach you by reflecting the beam of buildings.
Also note, to the antenna discussion: changing your devices antennas gains very little, especially since the mechanism of silent SMS is not to triangulate you based on the received signals of the towers, but by querying your phone for its measurements, which it then sends to the network.