All 4G modems can 3G and 2G?

Question

mobile connection

You need an inexpensive universal (2G / 3G / 4G) modem. What do you advise? And can you be sure that the 4G modem supports 2G channels?

Answer 1

To answer the question in the title, no. It can be different chips, maybe a hardlock.
And there is nothing to advise.