Information about this number from reverseau.com showed the number was to be from Netsip PTY. LTD. found here - https://www.reverseau.com/(03) 5939 5100.html

Understanding the Number (03) 5939 5100
The phone number (03) 5939 5100 is a local service number operated by Netsip Pty Ltd, located in Pakenham, Victoria, 3810. While it is associated with legitimate local services, it's always wise to remain vigilant when receiving calls from unfamiliar numbers.

A second search about this company found this news acticle from the Australian Communications and Media Authority - https://www.acma.gov.au/articles/2024-12/netsip-directed-comply-scam-rules

Title - NetSIP directed to comply with scam rules
Date of article - 17 December 2024
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The ACMA has directed telco NETSIP PTY LTD (NetSIP) to comply with Australia’s phone scam rules after an ACMA investigation found it breached monitoring, information-sharing and reporting obligations.

Under the Reducing Scam Calls and Scam SMs Industry Code, telcos are required to monitor and disrupt scams, share information about scam traffic with other telcos and government agencies, and report blocked scams to the ACMA.

The ACMA found NetSIP failed to share information about nearly 47,000 scam calls with other telcos and approximately 500,000 scam calls with the ACMA.

The information sharing rules are critical to enabling early identification and disruption of scams across Australian telco networks. A failure to notify other telcos about scam calls compromises their ability to take rapid action to protect their customers. A failure to notify the ACMA impacts the ability to identify scam trends and monitor that telcos are meeting their obligations.

Telcos may face penalties of up to $250,000 for breaching a direction to comply with an industry code.

Can't stop calling nearly every single day