Verizon customers experienced outages Friday across swaths of Southern California from Los Angeles to San Diego.
Customers began complaining on social media of problems making calls in the mid-afternoon.
A company spokeswoman said Verizon was aware of the outages but did not know what had caused them. Text messaging does not appear to be affected, she said.
"Verizon is currently experiencing a service disruption affecting voice service in parts of Los Angeles and San Diego and surrounding communities. Technicians are on site and working to resolve as quickly as possible," Verizon said in a statement.