FCC Chairman Tom Wheeler. (AP Photo/Pablo Martinez Monsivais)

Federal regulators have voted to impose new limits on telecom companies to be sure they don't use new technological advances as a way to wriggle out of obligations to consumers, such as ensuring reliable service, particularly in emergencies.

Companies, such as AT&T, Verizon and others, are in the process of upgrading the nation's telecom networks to high-speed fiber optic lines that can support more data and new features, such as high-definition voice and video calls. As part of that shift, telecom companies anticipate shutting off their old, copper phone lines — which are costly to maintain and aren't that commonly used anymore.

But there are still many Americans whose phone and Internet service still depend on those copper networks. And the Federal Communications Commission wants telecom firms to avoid simply cutting those people off.

"Changing technology is not a rationale for stifling service or competition," said FCC Chairman Tom Wheeler. "It does not bring the opportunity to walk away from the responsibilities that govern the relationship between those who build, and those who use the facilities."

The FCC has approved requirements that would, among other things, force carriers to tell their copper customers three months ahead of time if they're about to lose their service. They make it mandatory for carriers to offer comparable fiber optic service to business customers who currently rent copper services.

Phone companies must also offer consumers the option to buy back-up battery power for landline phones that run on the new fiber optic networks. That's because those new networks don't supply electricity to telephones, unlike the old copper lines. In an emergency, a lack of power could prevent Americans from calling for help. So under the new rules, phone companies will have to offer batteries that last eight hours. By the end of three years, they'll have to offer an even bigger option that lasts for 24 hours.