3G networks are shutting down soon. A scramble to get users to upgrade is underway

«I kept putting off [upgrading] since it was not my primary phone,» said Hommell, who used the iPhone as a work device for his Gulfport, Mississippi, law firm. «Eventually, a letter came saying they would be sending me a phone in a few weeks. I just waited and boom, there it is on my doorstep.»

Hommell, who was sent a new iPhone XR from AT&T (T) in October, is among the small segment of 3G holdouts who’ve received a free 4G phone from AT&T, which owns CNN’s parent company, ahead of its 3G network shutting down later this month.

«For nearly two years, we have been communicating with consumers via direct mail, emails and text messages and we will continue to do so as we help them navigate this transition,» AT&T told CNN Business in a statement. «This includes providing free replacement phones to a substantial majority of customers.» AT&T said the replacement devices tend to be 4G versions of smartphones that run on the same operating system the users had previously been using.

The 3G network launched in 2002 and became the driving force behind the early App Store boom around the end of that decade that followed the release of the first iPhone. Then the wireless companies moved on to 4G and more recently 5G networks. Now the three major carriers are moving to shutter 3G technology, with AT&T taking the step on February 22, T-Mobile (TMUS) doing so at the end of next month and Verizon (VZ) by the end of the year. As the technology officially becomes obsolete, a scramble is underway to help consumers avoid a disruption.

The shift will impact people still using 3G Kindles, 3G flip phones, the iPhone 5 and older models, various Android phones and some wearable devices. It will also affect home alarm systems and medical devices such as fall detectors. Some in-car crash notification and roadside assistance systems like OnStar will also need to be updated or replaced.

General Motors, for example, which owns OnStar, started pushing over-the-air updates in October to vehicles released as far back as 2015, including models from Chevrolet, Buick and Cadillac, that may be impacted by the transition. Some alarm companies are also urging customers to schedule appointments for technicians to fully replace their systems.

Even with these efforts, there’s a chance some customers (and devices) get left behind.

«There is always a risk of people losing service or devices being disconnected from the network,» said Dimitris Mavrakis, senior director at market research firm ABI Research. «Mobile operators make significant attempts to minimize this, but there will always be devices that are left out.»

Who’s at risk of losing service?

Only a small portion of wireless customers are still using 3G networks. Verizon said in a blog post that 99% of its customers have already upgraded to 4G LTE or 5G, and AT&T said less than 1% of its mobile data traffic runs on 3G networks. T-Mobile did not respond to a request for comment about its 3G userbase.

According to Roger Entner, analyst and founder of Recon Analytics, these combined estimates equate to about 3 million people. He suspects the holdouts «almost never use [their 3G device] and hence don’t get caught by the alerts when they make or receive a call.»

Those using a 3G phone have likely gotten texts, emails and physical mail from their wireless carriers over the past year urging them to upgrade. (If you’re not sure which network your phone is on, open Settings, tap Network and Internet, and then select Mobile Network on Android devices. On iOS, choose Settings, Cellular and then pick Cellular Data Options.)

Determining whether other household devices run on 3G may be a bit more complicated, however.

«These connected devices are at a greater risk of being disconnected from the network but individual vendors do spend time to alert their users that their 3G systems will be decommissioned shortly,» Mavrakis said.

Some companies, such as My Alarm Center, a home security systems business, are warning customers certain systems will need to be replaced by a technician to avoid potential disruptions. «Even if your alarm appears to function, it will no longer communicate with our central service station to notify us that emergency services are needed,» the company states on its website.

For mobile devices, however, there are some workarounds for people who don’t want to get rid of their 3G devices all together. In theory, it will be possible to access a web browser via Wi-Fi or make calls over wireless on a 3G phone if the user has an app enabling voice-over-internet protocol, such as Facebook Messenger. Similarly, people with a 3G e-reader will still be able to download new books on the device via Wi-Fi.

Mobile carriers are mostly not upcharging their customers to switch from 3G to 4G plans, likely to keep them from wandering off their data plans.

AT&T said «an extremely small segment» might have to change to a plan that results in a change in their rate. Sprint said anyone with a 3G device will be able to pay the same or less for 4G or 5G service from T-Mobile and can upgrade to a new device, including some 5G phones, at no cost. Verizon said customers are «strongly encouraged» to upgrade now and that it is «offering aggressive promotions.» (Verizon hasn’t said if it will be mailing users replacement devices as part of a last-ditch effort before its shutoff date.)

Will 4G be the next to go?

This is not the first time a network has been phased out nor will it be the last. The effort to shut down 3G is primarily to re-use the spectrum for 4G and 5G, which are newer standards, better technologies and more efficient than 3G. The same thing happened with 2G, which AT&T and Verizon shut down around the end of 2017; T-Mobile plans to shut its 2G network in December.

Last month, AT&T and Verizon turned on C-band 5G networks, an important set of higher radio frequencies that will supercharge the internet. The change will allow users to, for example, stream a Netflix movie in 4K resolution or download a movie in seconds. (Verizon said its C-band speeds reach nearly 1 gigabyte per second, about 10 times as fast as 4G LTE.

As 5G gains traction, and possibly 6G after that, 4G may be the next to get phased out.

Phones have arguably maxed out what’s possible with 4G at this point. The technology paved the way for on-demand apps such as Uber (UBER), mobile video consumption on Netflix (NFLX) and FaceTime, real-time rerouting via Google Maps, and social sharing on Instagram and Snapchat. But 5G could offer a doorway into what’s next — such as powering autonomous vehicles or enabling robotic surgeries — thanks to the ability to handle an uptick in traffic and bandwidth with no lag times.

As for whether another new smartphone might one day magically appear on his doorstep to replace the 4G iPhone he just received, Hommell said, «We can all hope for that.»