When I was on NExtel.....it would make my Monitor ( CRT back then ) and my speakers go haywire.........
since I switched to Sprint ( although they took over Nextel/merged with them ) my celphone has no affect on my monitor/speakers/PC
can just be the particular phone type/model you are using.....but yes some can and will interfer with your PC/Monitor/speakers.......
has more to do with the frequencies your phone is operating at vs your computer......( or speakers/monitor )
YMMV