The Australian Communications and Media Authority (ACMA) introduced rules to ensure mobile subscribers can access emergency services after Telstra and Optus switch off their 3G networks on 28 October.

In a statement, ACMA explained the measures call for operators to identify handsets unable to make emergency calls and notify customers within five business days.

The operators cannot provide services to devices identified as being unable to access emergency call services.

Operators also are required to offer information and assistance to customers to access alternative low- or no-cost mobile phones, and update payment assistance policies to allow people experiencing financial hardship to receive such devices.

Telstra and Optus delayed the closure of 3G services over concerns older handsets would not be able to support emergency calls on 4G and 5G networks.

The move was prompted by politicians, who raised the alarm over a potential lack of coverage in rural areas after the 3G shutdown.

Rival TPG Telecom shut its 3G network in January.

GSMA Intelligence estimated Telstra ended September with just over 36,000 3G users and Optus nearly 47,800.