The Federal Aviation Administration (FAA) imposed ground stops at Dallas Love Field and Dallas-Fort Worth airports on Friday afternoon due to a communication problem that resulted in over 300 flight delays.

The FAA said it was slowing traffic due to a reported local telephone company equipment issue that does not involve FAA equipment.

“The FAA is working with the telephone company to determine the cause,” the agency said.

The issues are expected to persist for several more hours.

The FAA has faced numerous communications issues this year.

Previously, on Thursday, the FAA had to reduce the flow of flights into Denver International Airport. This decision was due to automation issues between an approach control tower and Denver air traffic control, necessitating manual handoff procedures and leading to delays typically ranging from 30 to 45 minutes.

A sequence of challenges linked to the outdated U.S. air traffic control system led Congress in July to authorize an initial funding of $12.5 billion for its overhaul. FAA officials have pointed out that they are experiencing technological difficulties almost daily.

The FAA air traffic control network’s woes have been years in the making, but a rush of high-profile mishaps, near-misses, staffing shortages and a catastrophic crash in January between a U.S. Army helicopter and regional American Airlines AAL.O jet that killed 67 has spiked public alarm.