Could this be the end of the dreaded mobile blackspot?
OPTUS customers from today will be able to defeat network black spots by seamlessly using wi-fi networks to make mobile phone calls and send text messages.
Optus spokesman Ben White said the voice over wi-fi system would be particularly helpful for people who lived in a black spot area or had a room in their house that did not have good mobile coverage.
Mr White said this system was Optus's "cleanest" move yet in offering voice over wi-fi services and unlike the Optus Wi-Fi Talk app the system would automatically switch between using mobile and wi-fi networks
Because the system works with both public and private wi-fi networks in Australia, Optus customers travelling around the country will now be able to make calls on their phones even in towns without network coverage as long as they are connected to a wi-fi network.
The Wi-Fi Calling service will initially be available to Optus customers using the latest software on Galaxy S7 and S7 Edge phones.
Optus spokesman Ben White said the service would be expanded in coming months to include iPhones and other Android phones.
Once Optus customers opt in for the system, their calls will automatically transition to an available wi-fi network in Australia when the mobile network is limited, without interrupting a call.
Telstra launched a voice over wi-fi service last year that is available to customers with a Samsung Galaxy S6 and S6 Edge.
A Telstra spokesman said the service would be expanded next month to include customers with Samsung Galaxy S7 and S7 Edge smartphones.