If you remember, we reported earlier that BGR has confirmed with a trusted source that AT&T’s Flagship smartphones will be launching on October 21st. This will include the Nokia  Lumia 920. The sign-off of WP8 RTM edition also boosts the possibility of a nearer launch than November. If everything goes fine and Nokia and AT&T can finish testing the Lumia 920, which is already underway since or even before 5th Sep, the date of Lumia 920 announcement.

http://nokiapoweruser.com/2012/09/15/lumia-920-rumored-for-att-on-21st-october-windows-phone-8-rtm-sign-off-done-by-microsoft/

Now, this 21st launch possibility has grown much stronger with what Wpcentral has to report. They have been shared with some kind of internal AT&T document referring to 21st Oct as a very important date for Lumia 920. They further say though the word “Launch” has been used in that document, but still they bet it to be pre-order date rather than shipping date. They also mention that the source of this internal AT&T material had earlier confirmed the Mango-update dates for Windows Phone, which turned out to be very accurate.

However, Windows Phone Central has now come across new documentation circulating within AT&T that does indeed confirm the date of October 21st as an important day for the upcoming Nokia flagship phone. This is not the same info that presumably BGR saw (or was told) due to its recency. The language in the documentation clearly uses the word “launch” when discussing the Lumia 920, however there are mitigating circumstances that still makes it hard for us to believe. If we had to play it conservatively, we still may be getting the preorder date.

Unfortunately, due to our agreement with our source, we cannot share the contents of the message/documentation nor whom it was from, but be assured that we know that information and we are confident in its accuracy. Our source of the internal AT&T material had earlier confirmed the Mango-update dates for Windows Phone, which turned out to be very accurate. For that reason, we impart a high level of trust in this knowledge.

Source