Worth mentioning though is that the certification does not actually refer to the phone as the ROG Phone III. Instead it's labeled as the ZS661KS. The reason it's believed to be the ROG Phone III is because this is nearly identical to the ROG Phone II model number.
ASUS' current gaming phone. That model number is ZS660KL. So there are only two letters that have been changed. Which leads to the speculation that this is the upcoming gaming smartphone from the company.
Manufacturers also tend to keep the model numbers of subsequent phones close to previous models. So it would certainly make sense here for this to be the ROG Phone III.
Another ROG Phone III certification likely means ASUS is close to a reveal
It's already been rumored that ASUS was looking to launch the ROG Phone III in the third quarter of 2020.
But now with the certification a reveal may be closer than we think. For comparison, the Lenovo Legion Phone just received a certification in early June. And as of today Lenovo seems to have confirmed that the phone will be announced officially in July with the reveal being a part of that.
That doesn't necessarily mean that ASUS will do the same thing. But it could be an indicator to keep your eyes open. No doubt ASUS will let people know when it has an event to announce something big. But the certifications definitely help in pointing to possible time frames.
An accessory for the ZS661KS has also surfaced online
The certification isn't the only piece of evidence suggesting that ASUS' new gaming phone is on the way soon.
On a European website called Accessories ASUS, a USB cable is now available for purchase that says it's for the ASUS ROG Phone ZS661KS. The same model number suspected to be the upcoming ROG Phone III.
Now, this probably isn't an official OEM cable straight from ASUS. It might be, but it's just as likely that it's an aftermarket cable. The important thing is that it's for the model number that is likely the ROG Phone III. And if there are already accessories being sold for it, then the phone itself can't be far off from an announcement and a launch.
Take this with a grain of salt of course, because this isn't confirmed by ASUS. But again, it may suggest that ASUS is getting close to its announcement.