This topic has been discussed numerous times on PPRuNe.
Not sure if Boeing have tested the use of mobile phones in flight
Yes, Boeing leased a B747 many years ago (from memory from KLM), and after days of trying to find interference they could NOT.
I have been on Aircraft numerous times where all 3 of us on the flightdeck were using our personal mobiles, via own our servers, and there was also one installed on the flightdeck by the Company, never had any problems.
I would NOT like to see them in general passenger use, because of the nuisance factor, but it is NOT a safety problem.