The end of the road for original iPhone owners is here: AT&T has turned off its 2G wireless network.

It is a symbolic milestone, to be sure, since the first-generation iPhone can still function if it's connected to Wi-Fi, or even serve as an Internet-less gaming rig for the kids. But the original 2G iPhone is an AT&T exclusive, which means that as of Jan. 1, it has no way to receive cellular data, a severe handicap for the device that ushered in the smartphone era's most alluring prospect: accessing the entire Internet—not just a mobile version—in your pocket anywhere you go.

AT&T's decision to switch off 2G shouldn't come as a surprise, since it announced plans to do so in 2012. In a blog post on Monday, the company said that it plans to repurpose the 2G spectrum into its LTE network. It also said that it offered customers who were still relying on an original iPhone or other 2G device as their primary phone multiple chances to upgrade, including discounts and offers for free devices. AT&T says its 3G and 4G LTE networks now cover 99 percent of Americans.

Even as 2G marches toward extinction in the US, some companies continue to design apps for international users whose cellular access tops out at 2G speeds. Facebook, for instance, encouraged its employees to downgrade the Internet on their phones to a simulated 2G connection every Tuesday in 2015. The "2G Tuesday" plan was aimed at "building the best experience" for those around the world without 3G or 4G mobile Internet.

The move also comes on the tenth anniversary of the iPhone, which Steve Jobs unveiled at Macworld in January 2007. For more, check out our Visual History of the iPhone.