"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
AirPods and AirPower: Everything We Know
iPhone 7 Models From AT&T and T-Mobile Do Not Support CDMA Networks
A customer that purchases an iPhone 7 from Apple's website and selects AT&T as their carrier, for example, would be unable to later use the smartphone on Verizon, Sprint, or any other CDMA network, even if the device is unlocked. By comparison, all iPhone 6s and iPhone 6s Plus models worked on both GSM and CDMA networks.
A customer that purchases an iPhone 7 from Apple's website and selects Verizon as their carrier, on the other hand, would also be able to use the smartphone on AT&T, T-Mobile, Sprint, or any other GSM or CDMA network.
It was previously reported that Apple would switch to Intel modems for select iPhone 7 and iPhone 7 Plus models, including AT&T models, and Intel modems do not support the CDMA standard in the United States. That is likely the reason why AT&T and T-Mobile models are limited to GSM networks.
The same report said Qualcomm would supply modems for the remaining iPhone 7 and iPhone 7 Plus units, including Verizon and Chinese models, and this appears to be the case. Qualcomm modems support both the GSM and CDMA standard, which explains why the iPhone 7 from Verizon and Sprint will work on all carriers.
Qualcomm, which holds patents for WCDMA and CDMA2000 standards, is the main CDMA modem supplier in the United States. The company developed the first CDMA-based cellular base station in 1990, and since then it has licensed its technology to companies like Apple in return for royalty payments.
Until this year, Qualcomm was Apple's exclusive supplier of modems for LTE and Wi-Fi connectivity, which explains why the iPhone 6s and previous generations supported both GSM and CDMA networks regardless of carrier. But with Intel entering the mix, choosing which iPhone to purchase is now more meaningful.
The lack of CDMA support in iPhones with Intel modems may be short lived, fortunately, as Intel acquired CDMA assets from VIA Telecom in 2015. It is believed that this acquisition could pave the way for Intel to release its first LTE modem with both GSM and CDMA support as early as 2017 or 2018.
Ultimately, the most obvious choice should be to purchase a Verizon or Sprint model, even if you are an AT&T or T-Mobile customer, especially when considering resale value. However, some customers may have difficulty purchasing from another carrier, depending on their current status with their existing carrier.
Apple should also release an unlocked SIM-free model in the U.S., likely based on the Verizon/Sprint model, in a few weeks based on past launches.