Tips on buying a used iPhone?

[heimdal]

I'm in the market for an iPhone 3G, since prices seem to be dropping drastically with the release of the 3Gs.

I was wondering on what to look for when examining one in order to cover my bases. Call timer, for instance?

Any common defects that I should look out for that come with common use?

[tomtomtom]

I would say,

1.check the warranty status of the phone (Great if there are remaining warranty, can get phone replaced)
2.Scratch and cracks on the screen and back
3.Battery.

[breakdown79]

check the immersion sensors to see if the phone was ever dropped in water, which can cause issues with getting warranty service. There's one in the headphone jack at the top, and one in the dock connector. You may need to shine a light to see inside. If it's red, it means it's been in water. I saw a guy get denied service at the genius bar cause his phone had been in water. He kept denying it, but the genius just kept saying "I understand sir, but we have to go with the physical evidence."