Controversial former Telstra chief executive Sol Trujillo will return to the Australian tech scene, after signing on to be a director at fast growing Lachlan Murdoch-backed telecommunications and advertising technology start-up Unlockd.

The company has become one of Australia's closest watched startups, having attracted a range of big name investors from the Australian business community, locked in key deals with international telcos including a Sprint Telecom subsidiary and recently closed a $15 million capital raising to fuel its early international expansion.