Mobile number portability will allow customers to keep their number when changing mobile phone service providers.
Tony Shaw, ACA's chairman, said September 2001 would be the "earliest practicable" date for all providers to achieve mobile number portability.
"While new entrants to the market could be ready earlier, the established network oeprators face substantially larger tasks in making the necessary changes to their networks, billing and customer support systems," Shaw said.
"The ACA arrived at the September 2001 implementation date are very careful consideration of all submissions received on the preliminary view. These significantly challenged the practicality of the March 30, 2001 date and were given particular scrutiny."
According to Shaw, in addition to re-engineering networks, customers support systems and technical requirements, new commercial arrangements will be necessary for long distance, local and mobile service providers to pass phone calls to mobile users who have kept their number when changing providers.
The ACA's report on mobile number portability, Implementation Date for Mobile Number Portability in Australia - Final View, will be available on the ACA website.