You implied that cell phones don't work in flight above 2000 feet, but my own cell phone worked in flight to the point that I had to turn it off.
I didn't have long conversations on the cell phone because I was too busy doing such things as flying the plane, which didn't have a working autopilot, while looking out for other aircraft whose pilots sometimes failed to update their altimeters to the current setting for the location I was flying over, which sometimes resulted in their aircraft flying near my altitude, and navigating, so I simply told the callers I would call back. I also noticed that I was receiving text messages, which I didn't respond to until after I landed. This has been occurring off and on for many years because I simply forgot to turn off the phone before the flight.
I have posted those references for a particularly good reason, which shows that cell phones did work temporarily in flight back in 2001, but you also have to remember that the majority of calls were made on Airfones, not cell phones.