According to a report by the Wall Street Journal, Chinese hackers breached American telecom giant T-Mobile in a monthlong campaign of hacks against major American telecom companies. 

Possible Targets 
The journal claimed that the possible targets of the monthlong campaign remained high-value intelligence targets, citing people familiar with the matter. As per the reports of US authorities, high-ranking US officials remain the prey at the target of Chinese hackers.  

No Significant Loss 
T-Mobile said, “It is closely monitoring this industry-wide attack, and at this time, T-Mobile systems and data have not been impacted in any significant way, and we have no evidence of impacts to customer information,” to Techcrunch. 

Further, no specific information regarding traceability or data breach analysis has been publicized by T-Mobile, while it hasn’t disputed the journal’s report. 

Data breached 
No specific information regarding the type of information breached whether calls or texts has been reported either by WSJ or by provided by T-mobile authorities in their communication. 

However, the WSJ report also noted that the hackers seem to have harvested a large amount of internet traffic from internet service providers. Furthermore, there are signs that the campaign targeted a limited number of service providers outside the U.S. too. 

Attackers 
Citing people familiar with the matter, WSJ has reported that Salt Typhoon, a hacking group with potential links with the Chinese intelligence agencies is on the attackers' end. 

The Loophole 
The attackers tapped into the wiretap systems that US telecom and Internet Service Providers or Companies have been mandated to follow, under a 30-year-old law giving the government access to customer data.   

Warning to China 
The FBI and the U.S. Cybersecurity and Infrastructure Security Agency (CISA)  exposed this week, alerting the broader industry to a series of coordinated cyberattacks. They accused China of orchestrating a "broad and significant" cyber espionage campaign, specifically targeting the call records and text messages of senior U.S. officials, including presidential candidates.

Previous Instances 
A month-old report by CNN categorically mentions that Major US Telecom Companies like AT & T, Verizon & Lumen have fallen prey to such attacks by Chinese attackers only. However, this counts as the 9th attack on T-Mobile with the most recent one being reported last year which led to the theft of personal information from 37 Million T-Mobile customers.