The hackers used their access to telecom networks to target the metadata of a large number of customers, including information on the dates, times and recipients of calls and texts.

The overwhelming majority of people who own a cell phone rely on text messages for the bulk of their communication. However, multiple government agencies

Officials from the FBI and the US Cybersecurity and Infrastructure Security Agency say Americans' communications are vulnerable during cyberattack.

The FBI and Cybersecurity and Infrastructure Security Agency say that Americans should use encrypted apps such as iMessage and FaceTime to be safe from foreign hackers.