After a sustained silence, Apple has finally sent out invitations to an iPhone-related event on Oct.4 at its headquarters in Cupertino, Calif.

Let's talk iPhone, read the e-mail sent to reporters on Tuesday, suggesting the unveiling of the most anticipated next-generation device, dubbed iPhone 5 by the media.

After relentless speculation about the iPhone 5's release date, the phone, it appears, will come to retail stores in mid-October.

Some new reports have confirmed that AT&T has blocked employees from going on leave between Oct. 3 and Oct. 14, while Sprint, which has offered an unlimited data plan for the iPhone 5, has also reportedly blacked out retail employees from going on vacation in the first two weeks of October. Apple has reportedly done the same, with employees being denied leave between Oct. 9 and Oct. 12 and also Oct. 14 and Oct.15.

History suggests that the Oct. 4 event could indeed herald the public launch of the iPhone 5 launch in mid-October. Apple earlier unveiled the iPad2 on March 2 and the tablet went on sale on March 11, while the iPhone 4 was unveiled on June 7 last year and launched on June 24. Apple held an event in early fall to update iPod products as well as its iTunes digital music jukebox software.

Apple's iPhone has helped the company boost its revenue and reach record profit levels. The company shares rose by 0.6 percent to $405.68 on Tuesday. 

We believe a refreshed iPhone 5 will boast enough physical improvements to drive another strong adoption cycle, UBS analyst Maynard Um wrote in a note. There are huge expectations for the iPhone 5's features, including significant hardware and software updates.

The iPhone 5 is expected to adopt a teardrop design allowing for a slimmer and lighter model than the iPhone 4. It will be powered by Qualcomm chipsets and a dual-core A5 processor. The phone will run on Apple's newest operating system, iOS5, and is expected to feature iCloud service for operating iTunes and provide wireless remote access of music from all computers and mobile devices. It will feature an 8-megapixel camera with an improved flash unit. The iPhone 5 is expected to support between 16/32/64 GB of internal storage.

The iPhone 5 reportedly will not come with NFC support and won't be available on 4G networks.