Electronics have come a long way.
A basic “burner” phone costs around $50. These communicate either to a local cell tower that acts as a booster – if you’ve paid for the usage of it – or otherwise uses p2p communication for free. These generally lack the range of a proper phone, and require the cell or whoever you call to be within 2km.
More advanced phones are computers in their own right, often much better than the desktops today.