Internet and data services have been restored overnight to more than 90 businesses in Victoria's west that were disrupted by the fire that damaged the Telstra exchange in Warrnambool on Thursday.

About 50 technicians were now continuing to restore landline, broadband, mobile and radio services to the region's 60,000 customers following the blaze four days ago, Telstra said in a statement.

On Sunday night, crews restored internet service for 91 large businesses, including banks, medical and government customers.

Mobile services have been restored to more than 80 per cent of the area, with mobile base station coverage in Warrnambool East, Warrnambool North, Timboon and Allansford also fixed overnight.

Two Mobile Exchange on Wheels (MEOW) devices have restored coverage for 250 medical-priority assistance customers, as well as payphones in the region and 450 priority lines, including those for retirement homes and schools.

All communications services have been restored to the township of Balmoral.

Telstra hoped other townships would be back "on air" by this Monday afternoon.

"Technicians remain focused on restoring transmission cabling and replacing equipment which carries landline telephone services," the company said.

"Work will also be undertaken to restore coverage to customers in a number of townships by re-routing services through other exchanges."

The company has apologised for the inconvenience.

AAP