Is this warning about wireless modules interfering with aircraft systems true?
Quoted from: https://en.wikipedia.org/wiki/Mobile_phones_on_aircraft

In the U.S., Federal Communications Commission (FCC) regulations
prohibit the use of mobile phones aboard aircraft in flight.[1]
Contrary to popular misconception, the Federal Aviation Administration
(FAA) does not actually prohibit the use of personal electronic
devices (including cell phones) on aircraft.
Paragraph (b)(5) of 14
CFR 91.21 leaves it up to the airlines to determine if devices can be
used in flight, allowing use of &quot;Any other portable electronic device
that the operator of the aircraft has determined will not cause
interference with the navigation or communication system of the
aircraft on which it is to be used.&quot;

With the use of Wi-Fi on some flights the use of cell phones is permitted, through a Wi-Fi link. It would seem that the FCC has not relaxed its regulations as far as cell tower links by plane.
The issue is that planes move so fast that tower to tower hops would be continuous. With thousands of planes in the air the cell towers could be overloaded and drop calls.
However the use of a dedicated LAN Wi-Fi and low emission electronics had led to the airlines having the final say about cell-phone use and laptops. Ancient planes like the 727 could not block noisy devices on the plane, which affected cockpit instruments. Todays jet planes are much better shielded, and may offer a in-flight phone and local Wi-Fi, through controlled data pipes.