As anticipation of new iPhones mounts, an analyst has chimed in to predict Apple will release only one new model.

Apple is expected to hold a media event Oct. 4 to unveil iPhone 5, according to a report from AllThingsD.

Some speculate that Apple will have three models to address the low, mid and high-end markets. Theories about how a cheaper iPhone will fit into Apple's global strategy have flourished.

Al Gore, a board member, also hinted that Apple might release more than one iPhone.

But a Wall Street analyst isn't buying it.

We don't expect a second, dramatically different iPhone to accompany this as we don't think Apple needs to have three models in the market to address the high end, mid-tier and low end since the iPhone 4 (with memory lowered to 8 GB) will drop to $99 and effectively attack those markets, Wedge Partners analyst Brian Blair wrote in a note to clients.

Blair expects the focus of the new iPhone will be iOS 5, a speedier A5 processor and a higher resolution 8 MP camera with a small possibility of a larger 4-inch screen. 

On the casing, the analyst said: We believe the casing will be largely similar to the iPhone with some particular modifications to the antennae.

He added that Apple would hold its fall product event between Sept. 28 and Oct. 5 and the next generation of the iPhone and the iPod line would be the focus of this event. 

Our view is that pre-orders for the iPhone will start within days of the event and units will be available within 10 days of the start of pre-orders.  We believe the new iPhone 5 will offer slightly modified hardware on a faster processor, Blair said.

A 4S and a 5 Wouldn't Make Sense

The analyst questioned why Apple would bump up only the processor specs of iPhone 4 in addition to a newly designed iPhone 5 if the goal was to sell it into the pre-paid market at a lower cost. 

A 4S would simply cost more and a 4S itself wouldn't create a mid-tier market unless it was priced at $99 and the iPhone 4 went to $49 with the new iPhone at $199.  We see this scenario as unlikely, Blair said. 

The idea of the new phone being called '4S' with the same casing as the 4 actually makes sense. However, as that would follow the path of the 3G to 3GS transition, the analyst don't believe Apple would release a 4S along with a 5. 

It's one or the other in our view. And whatever Apple calls it, we are referring to it as iPhone 5 for now, the analyst said.

Blair expects iPhone units in the 24 to 25 million unit range for the September quarter as he don't believe iPhone sales have slowed globally even with a product refresh around the corner.

He projects December quarter units to be in the 27 million unit range, with the calendar year forecast at 90 million units, representing 92 percent growth from last year.