ShoreTel PBX switches are based on VxWorks and rely on solid state storage, not hard disks.

"ShoreTel is not as strong in SIP as Zultys, but that is changing quickly," he said. "The PBX has great features and benefits and it scales from SME to enterprise. Our largest customer has 12,000 users and there are about a dozen systems already installed in Australia."

Warhust said the company will hire "as aggressively as the growth requires it" and is looking to take an office that will accommodate support and training for customers and resellers so is "very serious about coming into this market".

ShoreTel is privately funded, cash flow positive, and has zero debt, he said.