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With the next generation of the iconic iPhone from Apple Inc. (NASDAQ: AAPL) imminent and a huge introduction expected to be announced from Cupertino next week, a myriad of new early upgrade programs are being offered. The telecom services analysts at J.P Morgan have taken a long look at ways that customers who are on/off-contract can upgrade to the latest and greatest smartphones. Obviously, customers on contracts that are not yet eligible for subsidized devices will have to pay more to upgrade. At least there are more options than ever to offset the increased cost by trading in (relatively new) old smartphones. Depending on the device and condition, customers can generally look to get at least $100 to upwards of $350 from trading in their old smartphones. Here are the top places for consumers to trade in and trade up to a new smartphone.

Gazelle is a private company to which you can sell your smartphone, iPad, iPod, even a Mac computer or Macbook. While it does not offer the best trade-in values, the sheer number of devices the company will buy makes it a great place for consumers to start looking.

Amazon.com Inc. (NASDAQ: AMZN) continues to offer a fantastic a trade-in program on recent iPhone models (3GS, 4, 4S and 5) and offers the best value for your trade-in. They offer on average $337 for the iPhone 5 16GB (in “good” condition) vs. Gazelle’s and Apple’s average offers of $312 (excluding the Sprint version) and $309, respectively. The downside is your payment only comes as an Amazon gift card. Plus, they only offer trade-ins for Apple iPhones and not other smartphones. Customers do get free shipping.

Apple’s trade-in program, which was launched late last month, has better prices than Gazelle, but not as good as Amazon. Customers can trade in any old iPhone for an Apple gift card at an Apple store or online with free shipping. Again, there are limitations like the Amazon offer, as you only can get the Apple gift card. However, it is a great plan for the Apple aficionado looking to trade up to a new iPhone. Apple does not accept any other smartphones on trade except their product.

AT&T Inc. (NYSE: T) offers a trade-in program, but it seems to require more personal information before offering a price, so the actual pricing offered is harder to be sure of. The company website lists a host of devices that you can trade in, but it is likely that only iPhones and the latest high-end Android smartphones will have any substantial trade-in values. The AT&T Next plan allows for a new smartphone or tablet every 12 months with “no fees.” A monthly installment plan payment is added to your bill.

Sprint Corp. (NYSE: S) has a trade-in program that really only gives the seller an account credit, which is great if you are an existing customer or looking to switch to the carrier. Like the other carriers, the value for your trade-in will be much higher at Gazelle, Amazon or Apple.

Verizon Communications Inc. (NYSE: VZ) program pretty much mirrors the AT&T and Sprint programs. It gives customers a Verizon gift card in exchange for the trade-in. Again, for existing customers or those looking to move to the carrier this may make sense. As in the other cases, consumers will receive more from the non-carrier locations.

Global system for mobile communications (GSM) devices, which are the ones that can operate on the AT&T and T-Mobile US INC. (NYSE: TMUS) networks, tend to have a higher resale value than the code division multiple access (CDMA) devices that work on Verizon and Sprint’s networks. This is because GSM models generally can be used everywhere overseas where the majority of the carriers use the GSM standard.

Smartphone use has become ubiquitous, and consumers do not want to be locked in to devices that will be less than the gold standard in less than a year. The carriers, retailers and the companies that make the products have all acknowledged this and are competing for your trade-in. The real question is what is the easiest and most cost-efficient way? The answer to that probably will change as fast as the smartphones do.

By now you certainly have seen that the wireless and telecom industry has consolidated into mostly a few major players. Here is a list of possible acquisition candidates that could still be acquired, along with some that likely cannot be.