HOUSTON – It’s been 24 hours since T-Mobile customers across Houston experienced a service outage due to a damaged fiber-optic line.

WATCH: Investigating T-Mobile's outage

The carrier restored service after four hours, but customers wanted to know what caused the disruption.

Will there be a refund or credit for the downed service?

KPRC Channel 2 News reached out to the T-Mobile corporate office, but didn’t hear back. After speaking with two different stores, it doesn’t appear there will be a credit or refund for the four hours lost.

What happened?

A construction crew working in the 600 block of Plaza Verde Drive, which is near I-45 and Aldine Bender, accidentally cut the cable, according to Comcast. The company said T-Mobile uses the fiber-optic line to provide service. It’s unclear what the crew was doing and if it was working on the lines.

What is a fiber-optic cable?

It’s a cable made up of tiny glass used to carry high-speed data.

“Your phone calls converted into pulses of light that move at an incredibly high speed and that’s how the system can handle all that traffic,” explained Dr. Chris Bronk, an assistant professor at the College of Technology at the University of Houston.

Are they fragile?

According to Bronk, they’re fairly easy to snap and break.

“It is really easy to break fiber-optic lines, that’s one of the reasons why they haven’t taken off in home applications for a lot of things,” explained Bronk. “In this case it’s a line, buried underground. It’s not really supposed to be messed with underground. (The) No. 1 killer of fiber-optic lines is typically backhoes.”

“The problem is fiber-optic lines have only so much ability to handle traffic, so once you have one line cut, you’re only going to have so much residual capacity in your other lines,” explained Bronk. “Really what it comes down to is, we probably need to think about if this kind of break is causing a major outage, T-Mobile probably needs to consider the idea of bundling more capacity together so more of those strands of fiber-optic cable linking Houston to other points, so they have more backup capacity at different places.”

It’s unclear what type of system T-Mobile has, but Bronk said when it comes to infrastructure in the United States, it’s different compared with other countries.

“We don’t subsidize a lot of infrastructure for telecommunications in this country, other countries do, that’s the difference,” explained Bronk. “If this was China, you have massive government subsidy for this kind of stuff, and still be a competitive market which is also good. How we put these companies to task on how much is enough (with infrastructure), we only really figure out when they’re having problems. They aren’t reporting to us on a day to day basis and they always tell us they’re spending a lot of money and they are, the question is how much is enough and what’s necessary.”