AT&T blames major network outage that downed 70,000 phones on a software update glitch while it 'expanded its network' - but the FBI and Homeland Security are STILL investigating

AT&T has blamed its network outage that downed at least 70,000 phones on a 'software update glitch'.

There had been speculation that the issue may have been the result of a cyberattack, but the company said there were 'no indications of malicious activity'.

It remains unclear where the problem originated and, despite AT&T's assessment, both the Department of Homeland Security (DHS) and FBI are investigating.

'Based on our initial review, we believe that today's outage was caused by the application and execution of an incorrect process used as we were expanding our network, not a cyber attack,' AT&T said.

'We are continuing our assessment of [the] outage to ensure we keep delivering the service that our customers deserve.'

It comes as tens of thousands of pharmacies across America are unable to get prescriptions to patients after a cyberattack on America's biggest health insurer.

Americans stood outside AT&T stores looking for answers to why they were without cellular service for hours 

AT&T staff appeared to have no answers for the group of frustrated customers standing outside a store

There is nothing to suggest the two events are related, but United said it believes its attack was a targeted, state-sponsored attack. 

The outage was first reported in the early hours of Thursday morning when customers were unable to make emergency calls, with multiple 911 centers reporting that users were unable to connect.

There were reports that other networks were affected, but this is thought to have been the result of failed attempts to place calls to AT&T numbers. 

Cyber experts told DailyMail.com the issue had hallmarks of a cyberattack, potentially an attempt by hackers to blackmail the company or steal user data.

The widespread nature, according to experts, seemed similar to 'a massive Distributed Denial of Services (DDOS) attack on core Internet infrastructure.'

Using DDOS, cybercriminals are attempting to crash a website or online service by bombarding it with a torrent of superfluous requests at exactly the same time.

The surge of simple requests overload the servers, causing them to become overwhelmed and shut down.

DDOS was deployed in 2016 when it knocked out major sites like Netflix, Twitter, Amazon and PayPal for hours. 

Lee McKnight, associate professor at Syracuse University in New York, told DailyMail.com: 'Reality is you cant rent DDOS as a service attacks by the hour on the Dark Web, so who exactly might be behind it may never by fully known/attributed.'

But the U.S. Cybersecurity and Infrastructure Security Agency (CISA) reported that 'the cause of the outage is unknown and there are no indications of malicious activity.' 

AT&T, Verizon and T-Mobile users reported early on Thursday that they are having network issues nationwide and in Canada

Still, National Security Communications Advisor John Kirby told reporters Thursday afternoon that DHS and the FBI were looking into the outage as well and working with the tech industry and network providers to see what can be done 'from a federal perspective to enhance their investigative efforts to figure out what happened here.'

While AT&T provided the answer of human error, how the outage played out has raised many questions, such as why were only some people impacted and others not.

McKnight told DailyMail.com that 5G networks rely on Network Function Virtualization (NFV) to operate, which is a cost-saving option for service providers.

NFV forgoes the need for expensive hardware, allowing service providers like AT&T to purchase cheaper switches, storage and servers to run virtual machines that perform network functions.

Compared to the physical equipment that is secured in a data center, network components that are virtualized are more susceptible to new types of cyber attacks.

And it is easier for malware to wreak havoc on virtual components than hardware components.

The NFV used by AT&T may have different virtual components throughout its cellular sites and a code error likely impacted just a certain group.

According to DownDetector , over 70,000 customers had been reporting outages on the AT&T network

McKnight suspected a specific hardware-misconfiguration and software combination was likely to blame.

The combination may have been included in some cellular sites, but not others in AT&T networks, which is why not ever customer experienced service disruption, he explained. 

On social media, customers poked fun at the company over the outage with some making memes comparing it Netflix thriller 'Leave the World Behind', which involves a breakdown in all technology as part of the plot.

Other customers meanwhile expressed their disdain at the outage, and demanded refunds from the company.

There has been no official reason given for the widespread drop in service, which has in turn fueled speculation on social media that hackers are behind the blackout. 

Customers poked fun at the company over the outage with some making memes comparing it Netflix thriller 'Leave the World Behind', which involves a breakdown in technology

One person said: 'SOS only. AT&T, T-Mobile and Verizon outage. Leave the World Behind trending?'

Another posted: 'Y'all ready to go and watch 'Leave the World Behind film now? Or you still holding out? AT&T/ US cellular outage/ SOS.'

Sharing a picture of Hunger Games character Katnisss Everdeen, one person said: 'Me after sending my final texts and leaving my WIFI riddled home to run errands on ATT's 'American's Oregon Trail provider' wireless network.'

Posting a video of a child on a swing while a fire burns around him, another person posted: 'Verizon users while AT&T users experience an outage.'

Another post states: 'T-Mobile, US Cellular, Verizon, AT&T all reporting nationwide outages, but I still have to hop on this Zoom meeting at 9am.'

While one other posted: 'Hey AT&T, did you try unplugging it, waiting ten seconds and plugging it back in yet?' 

Despite some making fun of the situation, other users demanded that the company refund them due to the blackout. 

Customers have poked fun at the the service, which is considered one of the most expensive networks

Despite some making fun of the situation, other users demanded that the company refund them due to the blackout. 

Oneuser posted: 'AT&T needs to give me my refund. This outage is unacceptable! Going the hotspot route this morning. Stay safe.'

Another added: 'I just paid my phone bill yesterday and now we're in an outage?? I need AT&T to cough up a refund/discount or something.'

While another said: 'One line + a device is almost $200 but over 30,000 people are waking up to cell service. I feel like this shouldn't happen. Where is my money going to?'

Clearly enraged, another user posted: 'This is f***ing ridiculous. AT&T, I switched over 1 year ago and it's not the 1st time our service is down. Fix this bulls***.'

One other person also demanded that their next bill be free, saying: 'I need my next bill to be free. I have top use my work phone's hotspot to tweet this.'

Another said: 'We're on a consumer cellular that's part of AT&T and we just use one phone. 

'Our bill is around $30 a month. A discount for all customers is warranted in March.'

While AT&T has said they are 'working urgently' to resolve the issues, customers have blasted the service, which is considered one of the most expensive networks.

In a statement, the company said: 'Some of our customers are experiencing wireless service interruptions this morning. 

'We are working urgently to restore service to them. We encourage the use of Wi-Fi calling until service is restored.'

The issue left AT&T iPhone users stuck in SOS mode, meaning that users can only make calls to emergency services.

Cricket, which is also part of AT&T, reported having 11,000 users down, while 2,800 Verizon customers are experiencing outages, with a further 1,000 T-Mobile users reportedly also being affected.

Service disruptions have been reported in New York, Boston, Washington, Montreal, Honolulu, Atlanta, Houston, Dallas, Los Angeles, Seattle and San Francisco. 

The carrier has more than 240 million subscribers, the country's largest.

On their website, AT&T have also said they are 'experiencing long hold times' and have apologized for the inconvenience.

Nationwide, 911 operators have warned that the outage has impacted their ability to take calls.

San Francisco Fire Department issued a statement saying they had been made aware of the issue and urged citizens to use try calling from a landline.

The major cellphone companies have yet make any statement regarding the outages

Flagler County Sheriff's Office in Florida shared a statement saying they had been unable to receive calls but text messages to 911 were being picked up

San Francisco Fire Department issued a statement saying they had been made aware of the issue and urged citizens to use try calling from a landline

The department added: 'If that is not an option then please try to get ahold of a friend or family member who is a customer of a different carrier and ask them to call 911 on your behalf.'

While Flagler County Sheriff's Office in Florida said they had been unable to receive calls, but text messages to 911 were being picked up.

Some have speculated online that the widespread outage could be a due to a hacking incident. 

One person posted: 'This AT&T outage definitely feels like a hack right? No service over here.'

Another commented: 'Weird. My AT&T phone works fine. Same phone and network right beside me just says SOS Why would that be? Software hack?' 

A spokesperson for T-Mobile told DailyMail.com: 'We did not experience an outage. Our network is operating normally.

'Down Detector is likely reflecting challenges our customers were having attempting to connect to users on other networks.'

While a Verizon spokesperson said: 'Verizon's network is operating normally.

'Some customers experienced issues this morning when calling or texting with customers served by another carrier. We are continuing to monitor the situation.'