"The Avaya offering is not based on open standards and we were concerned with the long term support [for] Asterisk," Reinhardt said. "The feeling was that if we became locked into a proprietary system we would not have much choice when we wanted to add an accessory from another supplier or improve functionality. With proprietary systems we would run the risk of additional costs down the track."

DSL's IT services manager Gerrit Brokken reviewed the Zultys solution and was happy to go to VoIP. "It is very flexible. With its advanced features and open standards platform, you can expand it easily as your operations grow," he said. "It allows you to do things internally, like change and add extension numbers, instead of having to bring in technical support people like you do with a proprietary PABX system."

DSL purchased a Zultys MX250 exchange for 28 users and 28 Zip IP handsets. In Malaysia it installed a Zip 2x2 handset, which is registered to the Perth-based MX250 via a VPN.

Reinhardt said DSL is satisfied with the features of Zultys' MIXIE software which provides mobile workers with instant messaging, inbound call information and roaming features when they are out of the office.

The MX250 exchanges support routing of voice, data, fax, and video content via traditional PSTN and ISDN circuits, and IP connections back to an ITSP.