An unknown problem caused Verizon Wireless customers to be out of service for more than three hours on Friday afternoon. Verizon spokeswoman Michelle Gilbert said two sites being out of service in the area caused the problems.

“These types of disruptions are not common,” Gilbert said. “We are not sure what caused the problem but all hands are on deck to make sure it’s fixed as quickly as possible.”

Users were unable to send text messages or place phone calls, but some reported an ability to receive text messages at some points during the outage. It's unclear how many users were unable to use their phones during the outage. Verizon reported a total of 94.2 million customers nationwide in July, according to Information Week.

After being alerted of the problem, crews replaced the radios in the two sites and service was restored at approximately 2:30 p.m. Gilbert said no further disruptions are expected.

Ben Freed covers business for AnnArbor.com. Reach him at 734-623-2528 or email him at benfreed@annarbor.com. Follow him on twitter @BFreedinA2