An American man, asked to resign from his job at Cox Communications, pleaded guilty on Wednesday to hacking into his former employer's network and shutting down telecommunications services, including 911 numbers in major US cities.

William Bryant, 38, of Georgia, pleaded guilty on Wednesday in a US court to one count of knowingly causing the transmission of information to a computer used in interstate commerce.

Bryant, after being asked to resign his position, remotely shut down portions of Cox's national telecommunications network on May 6, according to a news release from the US Department of Justice.

Customers in Dallas, Las Vegas, New Orleans and Baton Rouge, were left without access to 911 emergency services for hours.

Bryant faces 10 years in prison and a fine of up to $250,000 (£125,000). He is scheduled to be sentenced December 13.

“Hacking – intruding into and causing damage to a computer system – is a serious crime,” US Attorney David Nahmias said on Wednesday in a news release. “Such electronic attacks threaten our nation's technological infrastructure, and we will aggressively investigate and prosecute them.”

Cox spokesman David Grabert said that the company uncovered the security breach itself and then notified law enforcement authorities.

“It's unfortunate that this happened, but it's a testament to our acumen as a provider that our security and engineering teams were able to notice there was a problem and restore service so quickly,” he said.