Data breach at Japanese telecom giant NTT hits 18,000 companies. Japanese telecommunication services provider NTT Communications Corporation (NTT) is warning almost 18,000 corporate customers that their information was compromised during a cybersecurity incident. The data breach was discovered in early February 2025, but the exact date when the hackers gained initial access to NTT’s systems hasn’t been determined. “NTT Communications Corporation discovered on February 5 that our facilities had been subjected to unauthorized access,” reads the announcement. Third-party company: NTT Communications Corporation (NTT).