Verizon engineers have fully restored the network disruption that impacted some customers, the company said Monday night.
Anyone still having issues should restart his or her device, Verizon said.
"We know how much people rely on Verizon and apologize for any inconvenience. We appreciate your patience," a spokesperson said.
The company confirmed an "issue" in a post on X earlier in the day, saying that it was aware of the problem impacting some customers.
Many people were stuck in "SOS" mode on their phones, unable to send messages or place calls.
It was not immediately clear what caused the problem or how many users were affected.
A spokesperson said it began at 9 a.m. EST.
By 1:30 p.m. EST, the website downdetector.com was tracking more than 66,000 outage reports.
"This morning, I was in Indiana at the time, realized I had no data, couldn't open GPS. So, I had no idea where I was going. Fortunately, my friend had data," Vu Nguyen said.
Investigators from the Federal Communications Commission are looking into the outage.
SEE ALSO: AT&T says it has resolved software issue that caused an outage for some wireless customers
Customers in the Chicago area and Indianapolis appear to be the hardest hit.
The FCC is already investigating a similar outage with rival network AT&T back in February that impacted more than 70,000 customers.
Verizon's outage happened hours after the company announced a $3 billion plan for a third-party company to lease and manage its cell towers.