In a research note, Huberty said Apple could see its iPhone market share rise to an average of 10 percent in the top six iPhone markets if it signed agreements with multiple carriers to sell the popular device. The iPhone currently has four percent of the smartphone market.

UBS investment research analyst Maynard Um agreed that the iPhone should see more sales when Apple's exclusive deals with AT&T and international carriers end. Maynard upgraded Apple stock from "neutral" to buy and raised his target price on the shares from $265 from $170, while Huberty pegged the stock at $210 a share.

Time To Buy a New iPhone

Given analyst expectations, that means the iPhone's sales could skyrocket in 2011, when most of Apple's exclusive deals end. One example is Asia. When the exclusive deals with Asian carriers expire in 2011, consumers could purchase an additional 20.3 million iPhones. That's a significant number, considering that Apple sold about 5.2 million iPhones globally in its fiscal third quarter ended June 27.

What's more, Apple's iPhone margins appear healthy. Um said consumer demand does not appear to be moving toward the less expensive $99 3G device. He predicts Apple will enjoy 36 million iPhone shipments in 2010 and 40.5 million in 2011.

Considering that some consumers may be ready to trade in first- or second-generation iPhones in 2011, the future for Apple looks bright. In fact, Um expects at least 20 percent of the 2010 shipments will be from repeat buyers.

Neither Apple nor AT&T could immediately be reached for comment.

A CDMA iPhone?

As Current Analysis analyst William Ho sees it, Apple could surely sell more iPhones if it didn't have an exclusive deal with AT&T. But to understand the big picture, he said, one has to look at why the tech giant chose to do an exclusive deal with AT&T in the first place.

"I'm of the school that believes that Apple's addressable market is the GSM market, which is global," Ho said. "If you were looking at Verizon first, your addressable market is limited to only CDMA markets, which include North America, parts of South America, Japan and South Korea."

CDMA is not available in Europe and it's just coming into China. With all this in mind, Ho said, Apple chose to develop a GSM phone first. Whether Apple opts to invest in the development of CDMA iPhones is bounded by exclusivity -- at least for now. But will Apple develop a CDMA model for release in 2011?

"It's like anything. If you expand it to more technologies, of course you are going to sell more. Look at the Palm Pre. You've got it on Sprint and there is going to be a GSM version," Ho said. "Vendors like Palm and maybe others like Samsung and BlackBerry, they made multiple versions, but they are in it as a manufacturer. Whereas manufacturing phones is not Apple's core competency. They'll probably get into it more and more, but it remains to be seen."