Our sources have pinpointed that Apple will be announcing a single next-generation iPhone model codenamed “N42″ at the September 12th iPhone media event. This new iPhone N42 model is the iPhone 5 that we reported on back in May.

In May, we said that this iPhone contains a taller, 1136 x 640 resolution 4 inch display, improved internals, and more.

Back in May, we also learned that Apple was working on an iPhone 5 codenamed N41, but it appears Apple selected the N42 over the N41. This N41 iPhone also had NFC, which is reportedly not coming in the shipping N42.

Following our early reports, we posted several images of back metal casings for the new iPhone that also point to its thinner design and smaller dock connector.

Here is the part codes matrix for the new iPhone launch from a source at a well-known U.S. retail chain: N42A-USA -$199, N42B-USA-$199, N42A-USA-$299, N42B-USA-$299, N42A-USA-$399, N42B-USA-$399.  A + B signify black and white.

We also understand that this new iPhone N42 will come in the same prices as the iPhone 4S. With this, we speculate that the configurations will remain at the iPhone 4S’s 16GB, 32GB, and 64GB capacities.

We also are led to believe that pre-orders will begin soon after next week’s announcement. The new iPhone will not ship immediately in all countries.

We’ve also been told that there are several new accessories (which may be comprised of cases, cables, and adapters) ready to ship alongside this new iPhone N42. We previously reported that Apple would also showcase a string of new iPods at its event next Wednesday.