Filings with the Federal Communications Commission suggest that Apple is preparing to released new versions of both the Airport Extreme and Time Capsule.

The reports indicate that Apple is not intending to change the form factor of the units but is instead going to add a combined mode allowing its AirPort base stations to support both iPhones and other 802.11b/g devices operating at 2.4GHz, while also broadcasting 802.11n wide signals in the 5GHz band to maximize throughput for notebooks and devices such as Apple TV.

AppleInsider has also posted today that six new Apple product numbers have appeared in some inventory systems.

Stock of AirPort Extreme and Time Capsule units remain healthy in the United States but availability across some parts of Europe has become non-existent over the last few weeks.

The FCC documents can be viewed as follows:

AirPort Extreme: Authorisation Letter, Request for confidentiality, and Test report.

Time Capsule: Authorisation Letter, Request for confidentiality, and Test report.