I have a very nice Sennheiser headset that I used with my old phone, and it's got a 2.5mm plug. I have been unable to use it with the iPhone because the iPhone has a 3.5mm plug. I searched for adapters but they all seem like cheap no-name products. No-name products aren't bad as long as they work, but I'd rather get some suggestions from people who may have bought one that works well with the iPhone 3G. Anyone have any suggestions? Thanks.