An Optus spokesperson said its towers were affected by an issue with background technology operated by Telstra, and Telstra fixed the issue overnight.

The company apologised to customers who experienced a loss of service during the outage.

YESTERDAY: An Optus service outage has been impacting customers around Warrnambool this afternoon.

An outage affecting voice and text, internet and email is being investigated.

An Optus spokesperson said technicians had visited the Warrnambool site and were waiting on parts to restore services.

The spokesperson said the technicians were analysing the faulty parts to determine the underlying cause of the issue, and apologised to affected customers.