NEW YORK ( TheStreet) -- Though Apple ( AAPL) just announced the iPhone 5 a few months ago, the rumor mill is up and running again, as Apple soon will reportedly start testing the iPhone 5S. DigiTimesreported that Apple will start trial production of the new phone next month, with an initial volume between 50,000 and 100,000 units. DigiTimes has been spotty with its Apple rumor mill in recent months, calling for products that either did not exist or mixing up component supplies with the actual product. Take this rumor with a grain of salt. Apple has had success with the iPhone 5 though supplies are still constrained, as the device is vastly more difficult to make than previous versions of the iPhone. Not only is the phone bigger with a 4-inch screen compared to previous 3.5-inch screens, it has an aluminum backing, which scratches easily through normal wear and tear. The iPhone 4 and iPhone 4S had glass backings, which made the phone heavier. CEO Tim Cook noted on Apple's earnings call that demand is extremely strong for the iPhone, and the company has made progress in output. "The demand for iPhone is extremely robust, we are thrilled with what we see; we are in a significant state of backlog right now," Cook said on the fourth-quarter conference call. "In terms of the production, our output has improved significantly since earlier this month. And I'm very, very pleased with the progress that we've made there; I'm pleased with the current level of output in what is the largest volume ramp in Apple's history. It's difficult to predict when supply and demand will balance, but I'm feeling very confident on our ability to supply quite a few iPhones." Apple reported fourth-quarter earnings Oct. 25. The report also showed that Apple would release a new version of its iPad, despite Apple announcing both an iPad Mini and a fourth-generation iPad at its October product event. TheStreetcovered this event live. Apple will reportedly release the new iPad "a quarter later than the iPhone 5S."