Brits have been left unable to make calls after Three went down this morning, with Instagram also going down.
Customers of the network began experiencing problems at around 5am this morning, according to Down Detector.
By 8.45am around 1,500 people had logged issues, suggesting the problems may be widespread.
Several hundred people also reported that their Instagram app wasn't working between 8am and 10am this morning.
Three acknowledged there was an issue shortly after 7.30am.
'"Please accept our apologies if you've been affected by this, our engineers are working hard to fix it," the company said in a statement.
"Check back here for updates."
The bulk of the complaints suggested that making phone calls was the issue, with a smaller number registering problems with mobile internet.
People took to Twitter to log their complaints.
"Can’t make or receive calls. Your live chat is down. This is everyone on three is affected currently yes?" one woman tweeted at Three.
Another user posted: "Anyone having problems with @ThreeUK my whole family can't make or receive calls. #three #3 #outage".
One woman added: "@ThreeUKSupport I can't phone out or people can't phone me and it's the same for the people who are on #three network #help."
Facebook’s Santosh Janardhan explained what caused Instagram to go down.
“Our engineering teams have learned that configuration changes on the backbone routers that coordinate network traffic between our data centers caused issues that interrupted this communication," he said.
“This disruption to network traffic had a cascading effect on the way our data centers communicate, bringing our services to a halt.”
The outages caused fury among some users of the social media site.
One wrote: "here we go again".
Another very angry user wrote: "IS INSTAGRAM F*****G DOWN AGAIN? FFS".
Technology companies have had a bit of a tough time of it over the past couple of weeks.
Yesterday Snapchat went down for around four hours.
Last week all Facebook owned apps, including WhatsApp and Instagram, crashed for seven hours.
