Been jonesing to pick up one of the new smartphones that've been hitting AT&T lately? Starting tomorrow, AT&T will be making it even more tempting to do just that with a new trade-in promotion. The carrier has announced that on May 1, it'll begin handing out credits of at least $100 for device trade-ins that customers can turn around and use on any smartphone that AT&T sells. That includes iPhones, the HTC One, the BlackBerry Z10 and the Samsung Galaxy S 4.

AT&T subscribers that are interested in taking advantage of this offer can visit their local AT&T-owned retail store or participating authorized dealer and bring along a piece of mobile hardware that's no more than three years old and in good, working condition. AT&T says that it will accept smartphones, feature phones, tablets, netbooks and data cards, and products from carriers other than AT&T are eligible for the program.

After trading a device in, customers will be given a credit that can be used in a few different ways. Subscribers looking for a new device can put it toward the purchase of any new smartphone in AT&T's inventory (with a new two-year agreement), or it can be used to pick up some new accessories for a device that they already own. The credit can also be applied to a monthly bill or donated to the Cell Phones for Soldiers charity.

There's certainly no shortage of ways to get rid of old mobile hardware in order to upgrade to the new hotness. However, AT&T's new trade-in program looks like a pretty simple way for the big blue carrier's subscribers to free themselves of some aging phone or tablet and then turn right around and pick up a new device at a discounted price. AT&T says that customers can receive at least a $100 credit for hardware that meets its trade-in criteria, but in order to find out the exact amount that a product is worth, users should visit a participating store or use AT&T's trade-in appraisal page, which can be found right here. 

Via AT&T