Originally Posted By: drakino
This would be RF interference, and the iPhone 3G will be running on the same frequencies as the normal iPhone does now. AT&T runs most of their GSM network at 850 mhz, and this seems to interfere a lot with unshielded speakers and such. My AT&T razr did this, my friends T618 did it as well. T-Mobile tends to stick to 1900 I think in the US, so very little noticeable interference. I'm not sure offhand what frequency the other providers use.

It isn't the actual frequency that GSM transmits on that causes the issues. It is because the timing of the data bursts is at an audible frequency that actually causes the ditditditdit noises you hear on speakers/radios.