T-Mobile was also targeted by Chinese hackers alongside AT&T or Verizon, The Wall Street Journal reported Friday. Salt Typhoon—the name Microsoft assigned to a hacking group it linked to Chinese intelligence operations —breached T-Mobile’s systems in recent months and obtained access to an unknown amount of customer data.

The FBI has confirmed that Chinese hackers were responsible for a series of telecommunication breaches that may have lasted months.

This is the ninth known cyberattack to target T-Mobile in recent years, according to an ongoing count by TechCrunch.