Vodafone customers across Australia were unable to make or receive calls outside the telco's network for four hours on Wednesday due to a maintenance fault.
Customers started complaining of service issues around 1030am AEDT.
Calls could be made and received within the Vodafone network, but not to or from other mobile telcos.
Vodafone said data and text services were not impacted, but some customers reported being unable to send or receive SMS. It also said not all customers on the Vodafone voice network were impacted.
The issue was resolved at 2:30pm AEDT, Vodafone advised.
It attributed the outage to a fault that arose during scheduled work on the network, which caused voice traffic congestion.
"We apologise to customers for any inconvenience and thank them for their patience," Vodafone said in a statement.
The telco's customers suffered a seven-hour outage to voice, text, and data services last September in what sparked the re-emergence of the damaging 'Vodafail' movement of 2010-11.
It later offered customers 2GB of free data as compensation for the outage.