T-Mobile said hackers gained unauthorized access to some of its customers' personal information, including potentially phone numbers and call records.

It's the fourth time in recent years that T-Mobile has disclosed security breaches.

"We are sorry for any inconvenience this may cause you," wrote T-Mobile CMO Matt Staneff in an undated post to the company's website that was recently reported by outlets, including TechCrunch and CyberScoop. "We take the security of customer information seriously and, while we have a number of safeguards in place to protect customer information from unauthorized access, we will continue to work to further enhance security so we can mitigate this type of activity."

A T-Mobile spokesperson told TechCrunch the breach occurred in early December and affected around 200,000 customers.

The operator said the hack didn't expose the names on its customers' accounts or information like credit card information or social security numbers, but it did potentially include "phone number, number of lines subscribed to on your account and, in some cases, call-related information collected as part of the normal operation of your wireless service."

T-Mobile previously reported hacks in 2018, 2019 and 2020.

T-Mobile of course is not the first major corporation to suffer a security breach, nor will it likely be the last. Indeed, a cyber-espionage campaign linked to Russia was recently discovered across a number of US government agencies, including the National Telecommunications and Information Administration (NTIA), which oversees telecom policy and is part of the Commerce Department. The Russian hack also affected major tech companies, including Intel and Cisco.

"There are only two types of organizations: those that know that they've been hacked and those that don't yet know," Co-Founder of cybersecurity technology company Crowdstrike Dmitri Alperovitch said in 2016. (He has since left the company.)

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— Mike Dano, Editorial Director, 5G & Mobile Strategies, Light Reading | @mikeddano