[CountSessine]

That's interesting. It suggests that your iphone is typically on a 2G GSM network, rather than a 3G UMTS/HSPA network. GSM is known for causing audio interference because the TDMA transmission window cycles at about 200Hz.

Does your 3GS say '3G' on the status bar while it's interfering with your speakers?

[jonny_noog]

Usually at home, I see the little wifi symbol as it's hooking on to my router, but if I turn off wifi, your suspicion appears to be correct, I can see that it's on 2G at home. So yeah, that probably has a lot to do with the issue, thanks for the info. My carrier doesn't have the greatest 3G coverage in all areas, but they're currently IMO, the best of a not so great bunch of options in my country.

[ChRoss]

In my office room, hardly get the 3G status, but the phone signal is full. I had no problem with my previous phone (Dopod).

[CountSessine]

Was your Dopod GSM, UMTS, or CDMA? UMTS and CDMA phones won't do generate audio-domain interference. Any 2G GSM phone, from the most expertly-designed Nokia or Ericsson to the worst Huawei will interfere with your speakers.