Cooper, now chairman and CEO of ArrayComm Inc. (see Martin Cooper - The Spectrum Avenger), made the call that changed the world while crossing a street in New York City.
"That was probably one of the more dangerous things I’ve ever done in my life," he joked many years later. "Sophisticated New Yorkers gaped at the sight of someone actually moving around while making a phone call."
And they still would, if your handset were the size of a small sport utility vehicle.

Nice phone, Grandpa!
The great thing about that call (apart from the fact it wasn't made from a packed train carriage, or a movie theater) is that Cooper was calling Joel Engel, his rival and head of research at Bell Labs, to have the first cell phone gloat.
What Cooper didn't know, of course, is that folk would look more than a little ridiculous for quite some time to come.

What's my tailor's number, again?
Thanks, Marty. And happy anniversary.
— Gabriel Brown, Research Analyst, Unstrung
Mobile was very voiuce-centric in 2003. We were on the verge of mass-market mobile broadband at that time, but it wasn't quite there yet.