iakobos,
Thanks for the info, I know next to nothing about the characteristics of mobile phone operation, however, the interferance was genuine, as was the dial tones and conversation. At first we (the F/O and I) thought that it was the ATC controller having a private conversation whilst she was at work, but this appears not to have been so.
The location was just after Kuala Lumpur (almost overhead) to 200 nm Northwest of Kuala Lumpur. We were at 32000 feet, and the interferance only occurred on 133.8, a harmonic perhaps?
I'd be interested if you can do any detective work on this, it was not just nuisance value, it totally jammed the frequency.
Regards,
Old Smokey