A small number of iPhone 6S and iPhone 6S Plus devices are already live, but there's no sign of an 'iPhone 6C'

Apple is only testing out two new iPhones right now, according to a report picked up by 9to5Mac.

Mobile advertising platform Fiksu took a look through its traffic logs to see if it could find any new or unidentified Apple devices surfing the web or using apps. The search located two devices identified as the "iPhone 8,1" and the "iPhone 8,2".

It's worth remembering that the iPhone 6 was identified as the "iPhone 7,2" while it was in development, and the iPhone 6 Plus was known as the "iPhone 7,1." So these two new entries could refer to the iPhone 6S and 6S Plus, which we're expecting Apple to launch on September 9th.

Rumours started last year that Apple was working on an "iPhone 6C" model of the iPhone 6, with a 4-inch display (a bit like the iPhone 5C). But we have heard little since.

And there's no sign of an entry in Fiksu's logs that might correspond to an iPhone 6C. But this doesn't mean for certain that we won't see an iPhone 6C next month. (Evan Blass, who is often pretty reliable when it come to mobile device leaks, has said that Apple will release three new iPhones at the same time.)

Fisk's data also shows that the new phones are using a range of apps, including travel, games and lifestyle apps. Most of their use is coming from the US, but a couple hits came from the US and Brazil too.