Verizon Wireless engineers worked on fixing an issue with its high-speed wireless network in the early hours of Wednesday, the second high-profile service problem this month for the company that boasts it is the most reliable.

The problem follows a December 8 outage that prevented some U.S. customers from accessing the Internet on their wireless devices for about 24 hours.

By 11.30 AM spokesman Tom Pica said the No. 1 U.S. mobile provider's fourth generation (4G) LTE network was returning to normal but did not provide any details.

Throughout this time, 4G LTE customers were able to make voice calls and send and receive text messages. The 3G data network operated normally, Pica said.

Customers from around the country complained about the outage on Verizon's 4G LTE Community website, with reports of service problems in places as far flung as Houston, central Indiana and Seattle.

I'm livid. What happened to Verizon? I've been with them for years, but nothing but problems for the last few months, said one user.

Other users were still complaining later in the morning.

Verizon Wireless is owned by Verizon Communications Inc and Vodafone Group Plc.

(Reporting by Sinead Carew in New York and Jim Finkle in Boston; editing by Andre Grenon)