The official release date of the upcoming Apple iPhone 6S was unintentionally revealed when an internal email from United Kingdom carried Vodafone leaked. The email contains information pointing to a Sep. 25 release of the iPhone 6S in the UK region and it added that pre-order will open on Sept. 18.
According to Mac World, the email only states that a "New iPhone" will be released and did not state whether it is the iPhone 6S. Some speculation claim that the new iPhone the email is referring to might be the rumored iPhone 7.
Although the leaked email from Vodafone is lacking in some minor detail, it gives a room for estimate regarding the official release of Apple's new device.
During its 2015 Worldwide Developer Conference, Apple kept its silence and no news about the iPhone 6S or iPhone 7 were released. However, a closer look at Apple's recent announcement and previous iPhone release dates can somehow provide a rough timeline regarding the official release of its new device.
Apple announced that the iOS 9 will be officially released in fall. Incidentally, most of Apple's major device release was scheduled in September. The iPhone 6 and 6S were released in September 2014 while the iPhone 5S and 5C were released in September 2013.
Rumors claiming that both iOS 9 and a new iPhone device will be released simultaneously makes sense if based on Apple's previous release schedule.
With the announcement of iOS 9, the new iPhone will most likely be released running on the new operating system with full support of its features.
According to BGR, the new iPhone device will have the new Force Touch technology, upgraded Touch ID sensor, 2 gigabytes of memory, 12-megapixel camera and will use a faster processor like the Cortex-A9 from ARM.