Telco TPG has been fined $400,000 for blocking access to emergency numbers for customers with unpaid bills.
The contravention of the Telecommunications Determination was discovered when a woman was unable to call an ambulance for her husband, who was having a heart attack.
The man died in hospital just days later.
ACMA chairman, Chris Chapman, said it was the first time that ACMA had instituted proceedings against a telecommunications provider for contraventions of the Determination.
"This decision is a reminder for all providers that the obligation to give triple zero access is of paramount importance," he said.
"All Australians need to be assured that any call they make to the Triple Zero emergency call service will be connected."
ACMA began proceedings against TPG Internet in the Federal Court in November 2012 claiming that it had failed to ensure that its controlled network and/or controlled facilities gave the end-users of 5,979 home telephone services access to the Triple Zero emergency call service.
It also failed to connect 193 calls made to the Triple Zero emergency call service on 100 of those home telephone services.
In finding that TPG Internet had contravened the Determination, Federal Court Justice, Mordecai Bromberg, said the lack of immediate access to the emergency call service in the event of an emergency can have very serious consequences.
"Apart from the increased anxiety and stress involved for those seeking access, TPG’s failure could easily have led to the death of a person who might otherwise have been saved," he said.
According to ACMA, during the course of the investigation, TPG Internet advised that as a result of an error in a software upgrade to its systems, between March 15 and September 21, 2011, the end-users of 5,979 home telephone services, whose customers had failed to maintain an appropriate credit balance, did not have access to the Triple Zero emergency call service until the credit balance was restored.
TPG Internet became aware of the error in its system upgrade September, when it was advised that a customer was unable to access the Triple Zero emergency call service. The correction was progressively rolled out on the same day, according to an ACMA statement.
TPG Internet admitted that it had contravened one of the provisions of the Determination by failing to ensure that its controlled networks and/or controlled facilities gave the end-users of the 5,979 home telephone services access to the Triple Zero emergency call service.
TPG Internet did not admit that it had contravened another provision of the Determination which applies when a provider “supplies” a standard telephone service on which a call is made to Triple Zero.
TPG Internet argued that the provision had no application in relation to the 193 calls made to Triple Zero on the 100 home telephone services because it was not supplying standard telephone services to the customers of those home telephone services at the times the calls were made.