Perhaps IT support companies that provided similar services ie...

Perhaps IT support companies that provided similar services ie take care of all infrastructure, networking, internet and support etc are merely voice and data resellers (CSP under the Telecommunications Act) and perhaps not members of the Telecommunications Ombudsman Industry (TIO) Scheme in breach of the Telecommunications Act? Lookup https://www.tio.com.au/members for obligations to be a member and you can search if an IT support company dealing in voice and data (to end users) is a TIO member : https://www.tio.com.au/who-we-work-with

It is my understanding ST1 at least has a carrier license, owns communications infrastructure + deploys specialist comms integration software. I don't know of that many IT support companies that have these. I can name a few obvious ones: MNF, Telstra, Optus, Vocus, TPG, OTW and perhaps UWL.