There are several reports suggesting that Apple (AAPL) has begun final production of its next-generation iPhone already, but we have learned from a trusted source that this isn’t quite true. Apple goes through multiple stages before a product is manufactured, and two of these include the “engineering verification test” stage and the “design verification test” phase. Apple’s sixth-generation iPhone is currently in the EVT3 stage, the third revision of the engineering test stage, and has not yet entered the DVT stage. For reference, production of past iPhones was as follows, according to our source:

Verizon (VZ) iPhone 4: This hit the EVT2 stage in mid-November, hit EVT3 the last week of November, and got up to DVT2 in late December. iPhone 4: The unit that was lost in a San Francisco bar was in DVT stage in late March, and had hit EVT2 by mid-February of 2010.

It’s certainly possible Apple is producing engineering samples of new iPhones and has started manufacturing device enclosures to iron out any problems with the manufacturing line before real production starts, but that’s all that is happening at this point in time. The final version of Apple’s next iPhone — the one that you will buy — has not started production yet.

Additionally, we have confirmation that the units Apple is currently testing have 1GB of RAM, doubled from the iPhone 4S’s 512MB, and integrated 4G LTE radios. We can also confirm that NFC hardware is present in the phones as well. We’re expecting Apple’s new iPhone to be released at the end of September or early October.