(NewsNation Now) — As telecom companies rev up the newest generation of mobile service, called 5G, they’re shutting down old networks — raising concerns about the impact on technology like fire alarms, security alarms and even ankle bracelets.

The costly, years-in-the-works process is now prompting calls for a delay because many products out there still rely on the old standard, 3G.

3G has been around for more than a decade and a half, and it was the technology that helped make the smartphone era possible.

But after the launch of 4G and 5G, the telecom industry is shutting down 3G to free up bandwidth for newer services.

Here is what we know:

• Older phones won’t be able to call or text when 3G shuts down.
• Fire alarms that have not been updated, while they’ll still be able to make sounds if there is smoke, won’t be able to contact the fire department.
• Outdated burglar alarms won’t route to emergency responders if triggered,

An estimated half a million people have medical alert devices that run on 3G. The AARP is concerned those users may not know their gadgets won’t work anymore or won’t be able to replace them on time.

Additionally, a shutdown of law enforcement ankle bracelets could potentially allow thousands of offenders to go unmonitored.

The FCC has responded to concerns saying it is working to implement safeguards for older phones and devices.

So why not simply delay the 3D shutdown?

AT&T says delaying the shutdown would impact customers and their ability to use IT services which would result in more dropped calls.

The company also says the FCC doesn’t have the authority to stop its shutdown.

AT&T told NewsNation that it already pulled the plug on its 3G network this week. T-Mobile is shutting its 3G network down by summer and Verizon is scheduled to do the same thing in December.

The Associated Press contributed to this report.