I flew the J41 for Eastern between age 60/65 as I was unemployable elsewhere.
We had a number of problems with the pod smoke warning system which seemed to activate whenever mobile was used in a particular seat. The wiring for the system routed under that seat. When we got stroppy with the pax the system warnings always ceased
It seems that some systems and installations, designed before mobile phones, are vulnerable to induced surged when the mobile phone goes to high power seeking a mast. Some of these older systems are still used in modern aircraft.
It seems cable shielding is the key issue
That's a good example of proof that mobile phones can, on rare occasions, cause interference.
I also use the example of the Mythbusters test where they build a replica cockpit with a heap of instruments, used a mobile phone near it and a lot of the clocks went a bit crazy. But then they found that it happened because of the non-shielded wire they were using. They replaced all the plain wire with shielded wire and all the problems went away.
So for anyone to say that mobile phones can't affect aircraft systems, all you have to do is prove to me that 100% of the wiring on 100% of aircraft is perfectly shielded and I'll be happy.