Apple is reportedly gearing up to push the iPhone 5S into production later this month, aiming to release it in the fall.

The upcoming iPhone 5S is expected to make its debut in late September or early October, along with Apple's latest iOS 7 and potentially a low-cost iPhone.

While the next version of the high-end iPhone is set to enter production this month, Apple already started production of the purported budget iPhone last month, Jefferies analyst Peter Misek wrote in a note to investors on Tuesday, July 16. That low-cost model of the iPhone will likely cost around $300 to $400, added Misek.

The analyst further estimates that Apple will order 25 to 30 million iPhone units during the fall quarter, later boosting that figure to 50 to 55 million units for the holiday shopping season. Apple presumably plans to build roughly 5 million iPhone 4S smartphones, 20 million budget iPhones and 25 million iPhone 5S handsets for the quarter starting in December, notes Misek, without mentioning the iPhone 5.

"Although the large build plan indicates Apple's confidence in the new product launches, we remain cautious as our checks indicate mostly incremental feature upgrades for the iPhone 5S," Misek wrote in his report, as cited by PCMag. "The Galaxy S4 continues to take share and the iPhone 4S will also have to compete with Google's Moto X phone."

In other words, the iPhone 5S will not sport any major differences in terms of design, so it will look fairly similar to previous iPhone iterations. That shouldn't come as a big surprise, however, as the "S" moniker suggests a refreshed version rather than a completely different iteration, just like the iPhone 4S launched as a refreshed iPhone 4.

Keep in mind that this is just a prediction that may or may not prove to be accurate. Misek's forecasts didn't always turn out to be true. For instance, the analyst previously predicted that the iPhone 5S will go into production in March, gunning for a June or July release, which he now contradicts with his latest forecast. Moreover, last year the analyst also predicted that an Apple-branded TV set was imminent, and that didn't prove to be true either.

In conclusion, it's always best to take such news with a grain of salt until things get official. If the iPhone 5S is indeed on track to make its debut this fall, it shouldn't be long until Apple makes an official announcement.