Telstra had applied to be freed from its obligations to provide regulated services for Optus's Hybrid Fibre Coaxial (HFC) cable network.
But in September the ACCC released a draft decision which rejected this proposal, stating that the exemption would not be in the best interests of end users.
Singling out a particular competitor would result in a discriminatory access policy. This could discourage investment in the Australian telecoms industry, the ACCC said.
And Telstra's strong position in the pay-TV market, as represented in its interest in Foxtel, would "likely limit" any competitive benefits the exemption would provide.
"The ACCC considers that open and equivalent access to all parties continues to be an important issue in communications regulation," said ACCC chairman Graeme Samuel in a statement.