Hate to bring up old news, but at the field today, one of our new pilots was doing a great job flying a 4-star 60 around, and his cellphone rang. he dutifully handed the Tx to his instructor and answered his phone, then took the radio back and finished his flight. Us 'hangar flyers' who were watching got to talking about what we'd heard, read, etc about cellphone interference, and I brought up this article I read in R/C REPORT magazine, the July 2005 issue. There is an article by Tony Stillman (Radio Ramblings) that is a 'should read' regarding rf interference between cellphones and out Tx's.

Experiments done by the School of Mechanical and Aerospace Engineering at Oklahoma State University showed a definite interference problem with synthesized frequency transmitters, specifically the Futaba 9Z Tx using synthesized frequency modules. Interesting reading.