Calculating the link budget of antenna and receiver with free space-path-loss formula

I really know that the real calulation of the range of UMTS, GSM or LTE antennas is depending on a lot of issues, reflection, and other stuff which makes it really complex.

I need only a rough model which I can calculate the range of them, so I thought I use the free-space path loss formula and look for the "r" in the formula. Is there anything wrong with my idea? Despite the fact that of course in really you'll almost never have just a free space but rather buildings,hills and other stuff but lets say, for my model I say there is nothing that disturbs my signal.....

If I can use the formula, my question would be so the only difference of those systems would be the frequency and the transmitted power or received power of the mobile phones, is that correct?

https://en.wikipedia.org/wiki/Free-space_path_loss

The usual $r^{-4}$ round-trip link loss is based on the antenna being a point radiator, or at least so far from the target as to appear almost like a point radiator. The full formula has all sorts of correction factors (aka "fudge factors") for the actual beam profile, and targets are represented as a standard shape of equivalent total reflectance, e.g. a sphere or a flat plate mounted perpendicular to the propagation axis.