Leeds and Yorkshire residents reacted with various emotions: fury, bafflement, apathy and more.
The outage is said to be affecting a total of 30 million people.Why is O2 down? This is the latest statement from the mobile network operator
O2 said: "Outage Update: Our teams are working closely with one of our 3rd party suppliers who has identified an issue in their system which has impacted mobile services globally.
"This is our top priority and we are really sorry."
How you reacted to the O2 outage
Anthony Roberts said : "Well. This is what happens when you vote leave. This is Brexit's fault. Because of Brexit the Russians are meddling with use to wind up Trump."
Liam Storey said: "Oh no! All of the kids and teens are actually going to have to converse with each other"
Fin Keating: "Tell O2 to turn it off wait 30 seconds, then turn it back on again"
Jenn Hurley "It's days like this where I'm glad I'm not working for O2 customer services anymore. I can only imagine the number of abusive phone calls my former colleagues are having to deal with today"
Katie Elizabeth: "Well I hope we're all getting a good will gesture for this O2!!"
Muhammad Tufail: "My not working since 5,30 this morning."
Adele Faye Sissons "this is why you couldn’t get online! I’ve been resetting my phone all morning "
Sarah Marie @lou_lou_belle34 said: "The absolute panic today with O2 being down just goes to show how almost pathetically dependent we all are on our phones. Pretty sure the world would still function if we all had to actually communicate by speaking to each other in other ways (the horror) #02down."
Lauren Barry said: "Reading the #O2down tweets today has given me so many LOLS. I’ve spent the last eight hours without any service but I STILL don’t feel the need to attack the poor @o2 social media team over it! Get a grip.