State regulators have opened an investigation into concerns about unreliable phone service in a part of southeastern Utah.

The Utah Public Service Commission in late June consolidated two consumer complaints and the inquiry into a single case, since all arise out of quality concerns with Frontier Communications of Utah. The state’s public utilities division has already been looking into these issues, and the commission asked that the agency share the status of its investigation by July 8.

“The next step is for parties to make more specific process updates and recommendations,” Michele Beck, director of the Utah Office of Consumer Services, wrote in an email this week.

State agencies have been examining Frontier’s service after Moab resort operators and a Castle Valley resident submitted separate complaints about intermittent phone outages. The owner of Sorrel River Ranch Resort and Spa has said she cannot calculate the monetary damage her business has suffered from lost bookings because of dropped calls and downed service.

For decades, Frontier has held a state certificate that grants it a monopoly for landline service in much of southeastern Utah, including San Juan County and parts of Grand, Wayne, Garfield and Kane counties. Carriers that hold these “certificates of public convenience and necessity” must generally agree to furnish safe, adequate and reliable service to all customers with a hookup.

Frontier has defended itself by describing the challenges of maintaining a telecom network in rugged and isolated terrain. Recent problems in the Castle Valley area were related to the December installation of a radio network and the difficulty of troubleshooting the new equipment during winter weather, according to the company.