Verizon said its network has been fully restored, making cell phone service available again to customers across the country after an outage on Monday left many people unable to make or receive calls for much of the day.

People across the country said their phones had no service except SOS mode, meaning their phones were having trouble connecting to a wireless network. However, when a phone is in SOS mode, it can still make emergency calls, such as 911, by connecting to other carriers, according to Apple.

The outage began shortly after 9 a.m. ET on Monday and lasted into the evening. At 8 p.m., Verizon told CBS MoneyWatch that its engineers had fully restored the network after an “outage that impacted some customers.”

“Services have returned to normal levels,” the spokesperson said.

What should I do if your phone is still in SOS mode?

Verizon said people who are still having trouble connecting to the network should restart their mobile device.

People with iPhones can also try reconnecting to their cellular network by going into settings, turning on “airplane mode” for at least 15 seconds, and then turning off airplane mode, Apple said.

“We know how many people rely on Verizon and we apologize for any inconvenience caused. We appreciate your patience,” Verizon said.