It is now certain that iPhone 6S and iPhone 6S Plus are coming this fall. Ahead of the official confirmation from the maker, we have been treated with several leaks and rumours about what to expect from Apple's next flagships.

Going a step further than teasing the expected features, a German carrier has opened pre-booking for those who wish to be first in line to purchase the new iPhone 6S and 6S Plus when available.

Deutsche Telekom has set up a dedicated online reservation system for iPhone 6S and 6S Plus and it promises preferred delivery of the new iPhones, as reports.

In order to participate, customers must sign up with valid information such as full name, address, contact number and email address. The early pre-order setup from Deutsche Telekom does not require customers to pay anything and is likely to be valid in Germany only.

This is not the first time Deutsche Telekom has set up an early reservation for a new iPhone ahead of the official release. In 2011, the company had set up a similar pre-order system weeks before Apple officially unveiled the iPhone 4S.

Based on the reports so far, we have discovered that iPhone 6S will feature notable upgrades compared to iPhone 6 and iPhone 6 Plus. The Cupertino-based tech giant is likely to integrate Force Touch display in the new iPhones along with sizable upgrades to the camera, RAM and the processor.

A report from last week suggested Apple is going to hold a special event on 9 September, which has largely been linked to the release date of the new iPhones, Apple TV and long-rumoured iPad Pro. With the official launch just weeks away, Deutsche Telekom's pre-booking set up checks out just fine.

Last month, T-Mobile also promised a seamless upgrading facility to the latest iPhone 6S this fall. T-Mo subscribers who recently upgraded to the new iPhone 6 won't have to pay anything initially to upgrade to the new iPhone 6S but simply pay $15 a month for 18 months.