S4 Mini has a 1.7GHz dual core processor for fast Internet, apps and downloads, 8 MP rear and 1.9-MP HD front-facing cameras.
Samsung today also unveiled among the world's first dual band 4G (Time-Division Duplex and Frequency Division Duplex) capable devices - the Galaxy S4 mini and a new S4 version, that runs on Optus.
But there's also a 3G version of Mini available.
The Galaxy maker confirmed the new S4's will be made available on other networks "soon."
For those who hate bigger screens, the Galaxy mini is easy to carry and operate with one hand - weighs 107g.
It has some cool stuff on the camera like Sound&Shot, which stores sound and voice as pics are taken, Panorama Shot, Story Album auto gathered and saved according to user's timeline, geo-tagging.
Apps include WatchOn (to watch live TV, movies), S Translator, S Travel, S Health.
The GALAXY S4 mini comes in White Frost and Black Mist on sale from August 28 from Optus and select retailers.
Plans include $50 (+ $5 handset fee) a month, with 450 mins of standard calls, unlimited standard SMS and 500MB of internet data.
Outright price is $576. The larger Galaxy S4 Dual Mode LTE available in September, available outright for RRP $744, or $7 handset fee on Optus $60 plan, from mid-September.
"Being first-to-market with world leading devices that are supported by a premium TDD-LTE network represents a milestone for mobile technology in Australia and is indicative of the constantly evolving collaboration Samsung maintains with leaders in telecommunications networks," said Tyler McGee, VP - Telecommunications, Samsung.