I think we've been using this term long before mobile phones... This feels a bit like the word "bug"; I'd be quite interested to know if it can be traced to it

I think we've been using this term long before mobile phones... This feels a bit like the word "bug"; I'd be quite interested to know if it can be traced to its actual first use. People associate it with phones because as I remember they were always being described as the size (and weight) of a brick, and that's when they were working.