Lumen’s confirmation comes after U.S. telecom giants AT&T and Verizon confirmed to TechCrunch that they had also secured their networks following their breaches. T-Mobile, another Salt Typhoon target, said last month that it had no evidence of hackers still in its systems.

The telecom companies say they're no longer detecting activity from foreign entities that were hacking their networks.

The Chinese-linked Salt Typhoon cyberespionage operation targeted AT&T and Verizon's systems, but the wireless carriers' U.S. networks are now secure as they work with law enforcement and government officials,