UPDATE, 6.30pm: Telstra has tweeted that voice calls on mobile phones are "up and running again".
"We'll continue to monitor and we're sorry for the impact on your Friday night", the company tweeted.
UPDATE, 5.45pm: A Telstra spokesperson said the company is continue to work on the issue.
"We're continuing to look into the issue that's causing intermittent issues with voice calls on mobiles," the spokesperson said.
"Data and messaging are OK and you can use apps like Facetime or WhatsApp as a back up to make calls. We'll give you an update when we know more."
EARLIER: People are unable to make calls on the Telstra network as the company works to fix issues with connectivity.
The national phone company tweeted that some people were having "intermittent issues with making calls".
"Data and messaging are OK. We'll give you an update when we know more," the tweet said.
A second tweet said data was work and apps such as Facetime can be used to make calls.
Have you signed up to the Bendigo Advertiser's daily newsletter and breaking news emails? You can register below and make sure you are up to date with everything that's happening in central Victoria.
Sign up for our newsletter to stay up to date.