(Pocket-lint) - Developers have revealed that Apple is currently testing its next phone and operating system, and it's the iPhone 6, not iPhone 5S.

Traces of a device that comes under the designation "iPhone 6.1" have been popping up in app logs - the iPhone 5 was listed as "iPhone 5.1" and "iPhone 5.2" before its launch. The operation system name of "iOS 7" has also been spotted.

Apple annually updates its smartphone and tablet operating system. However, many observers and analysts were predicting that 2013 would be an "S" year for the company, meaning that the next handset would feature minor improvements over the last and therefore have an "S" tacked on to the name. We've seen the iPhone 3GS, iPhone 4S, and it felt natural that a possibly NFC-sporting iPhone 5 would be called the iPhone 5S.

One developer showed The Next Web the identifier "iPhone 6.1" and the site has also seen app logs that prove the IP address used by the mystery device to indeed come from Apple's Cupertino campus. As the site suggests, while it is possible to fake the designation and operating system of a phone, the location at which it was being used is a good indication that it is genuine.

Sadly, there are no further details on either the iPhone 6 or iOS 7 - logs traditionally do not give away such nuggets - but sources have previously suggested that Apple began working on the next mobile operating system at the end of 2012.

Writing by Rik Henderson.