The US Federal Communications Commission (FCC) has called the hours-long outage of T-Mobile's network an unacceptable failure on its part in providing quality service to its subscribers. Following the nationwide shutdown of its network on Monday, the FCC stated that it was going to be launching an investigation in the company's operations.

Around noon ET on Monday, T-Mobile announced that it was experiencing problems with its voice and text wireless network. One of the country's largest cellular network service providers was able to resolve the issue at around 1 a.m. on Tuesday.

On Tuesday, FCC Chairman Ajit Pai mentioned in a post on Twitter that the agency, along with thousands of affected American consumers, is demanding immediate answers for the outage. The hashtag #TMobiledown surged to the top trending topics on Twitter during the day, with thousands of consumers noting the issue. The outage generated a lot of speculations amongst the public, with some alleging that it could be a precursor to an attack or a result of a hack.

According to the company, the issue was traced back to an internet-traffic error that caused a cascading problem within its network. Both AT&T and Verizon, two of T-Mobile's main rivals, reported no problems with their networks during the outage.

Due to the fact that their networks were not able to connect with T-Mobile customers, there was an impression of nationwide communications failure throughout the day. Text messages and calls to T-Mobile subscribers were not possible throughout the outage but calls between Verizon and A&T reportedly had no issues.

The FCC had previously fined networks for extended outages. In 2014, the telecommunications regulator slapped a $17.5 million fine on T-Mobile after it experienced two major nationwide service outages during the same day. During the outage, customers were unable to make important calls or send messages, including calls to emergency services.

Monday's outage had raised the same concerns, particularly from public-safety officials, who noted that the disruption had prevented some people from calling 911 and other emergency services. In response to the outage, some police and emergency departments had turned to social media to inform residents of alternative ways of contacting them. In Redmond Washington, the local police department made a post on Twitter, informing T-Mobile customers of an alternative method of getting in contact.

T-Mobile recently became one of the country's top three carriers, along with Verizon and AT&T, after it acquired Sprint. The company is currently still in the process of integrating its network with Sprint's systems. It is not yet clear if the outage was caused by some error in the integration process.