With Apple’s next media event on the horizon, iPhone 5 production has already ramped up overseas. Foxconn, Apple’s main supplier, is allegedly building 150,000 iPhone 5 units per day.

The supply chain is expected to reach 5-6 million iPhone shipments during September, with Apple’s next gen iPhone announcement expected to drop at the end of this month or in early October.

Digitimes reports:

“Suppliers in the iPhone 5 supply chain in Taiwan have geared up production recently with volume shipments of the new Apple smartphones to begin soon. Production of iPhone 5s at OEM maker Foxconn Electronics has reportedly reached 150,000 units per day, according to industry sources.

Shipments of iPhone 5 from the supply chain are expected to reach 5-6 million in September and top over 22 million units in the fourth quarter as suppliers will ship less iPhone 4 and CDMA-version iPhones during the final quarter of the year, noted the sources.”

Another report has claimed that Apple will sell more smartphones than any other company in 2011, with a staggering 86.4 million units expected to ship by year’s end.

We’ve already heard that suppliers have begun iPhone production, but have not yet installed iOS 5 on the devices. Apple has allegedly seeded the final build of iOS 5 with text-to-speech and FaceTime over 3G capability to carriers for testing. Once iOS 5 has been verified as ready for prime time, the software will be installed on Apple’s new devices.

While these supply chain reports are helpful to see that Apple is gearing up production, the rumor of a second, cheaper iPhone model remains a mystery. Most likely, Apple will slightly re-tool the iPhone 4 and sell it as a cheaper offering with heavy reliance on iCloud storage. Perhaps the rumored device’s alikeness to the current iPhone 4 explains why no mention has been made from supply sources overseas.

[Electronista]