ACMA, which issued the warning, said it formed the view that Bytecard has contravened the service provider rule which requires compliance with the TIO scheme.
Both the TIO and ACMA said they had made attempts to encourage Bytecard to voluntarily comply with the scheme, without success.
Netspeed's manager, Brian Morris, was unavailable to comment until "the week after next".
Other staff members at the ISP also declined to comment to iTnews.
"It is the obligation of all members of the TIO Scheme to comply with the obligations established under the scheme as well as the legislation that governs the industry," said Chris Chapman, ACMA Chairman.
"ACMA will pursue the appropriate enforcement options open to it in order to prevent Bytecard from continuing to contravene its regulatory obligations."
The TIO scheme was established to deal with complaints by residential and small business customers of carriage services.