San Francisco

US telecommunications giant T-Mobile has suffered a security breach that may have exposed call records and phone numbers for some of its customers.

According to T-Mobile, the data breach did not expose account holders' names, physical addresses, email addresses, financial data, credit card information, social security numbers, tax IDs, passwords or PINs.

First reported by Bleeping Computer, T-Mobile said the breach exposed customers' proprietary network information (CPNI), including phone numbers and call records.

"Customer proprietary network information (CPNI) as defined by the Federal Communications Commission (FCC) rules was accessed," the company said in a security update.

"The CPNI accessed may have included 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", it added.

Earlier breaches at T-Mobile exposed customers' information in 2018, prepaid customers' information in 2019 and exposed customer and financial data in March last year, the report mentioned.

T-Mobile said the fresh breach affected a "small number of customers (less than 0.2 per cent)."

T-Mobile has approximately 100 million customers, which equates to around 200,000 people affected by this breach.

The company was alerting affected customers that a "security incident" exposed their account's information.

"The data accessed did NOT include any names associated with the account, financial data, credit card information, social security numbers, passwords, PINs or physical or email addresses," T-Mobile said.