Antarctic researchers are putting the freeze on call costs to the ends of the earth thanks to the Asterisk open source VoIP system.
The Australian Antarctic Division looks after all of Australia's interests in Antarctica including four research stations - the Casey, Davis and Mawson bases on the frozen continent as well as a base on Macquarie Island. The AAD is also responsible for the supply ship Aurora Australis, which carries people and supplies between Hobart and the remote stations.
Before the mid-1980s the stations relied on radio communications with Australia, which were only available for an hour or so each day. Later the four stations relied on IntelSat satellite voice links to communicate with each other and the outside world - with a traditional PABX handling call transfers within each station. This was originally accompanied by a paltry 4800 baud data circuit. The recent introduction of 384 kbps satellite data links to Casey, Davis and Mawson (plus 256 kbps to Macquarie Island) means the Australian Antarctic Division can fully embrace the benefits of VoIP already enjoyed by the rest of the world.
Each station has replaced its PABX with an Asterisk open source VoIP server to take advantage of the new data links. The Asterisk boxes link to some of the world's most remote Local Area Networks to divert calls throughout the many buildings that make up each station.
After two years of successful trials, the Australian Antarctic Division is cutting the separate satellite voice links to the bases, says Australian Antarctic Division telecommunication manager Peter Yates.
"We'll now operate all of our VoIP communications, as well as all of our data, across those data circuits which allows us to utilise the total available satellite bandwidth for data traffic, when VoIP voice calls are not in progress," Yates says.
"We also have an Asterisk server here in Hobart that handles calls between the stations and connects external calls, destined for the public telephone network, through a Telstra interface here in Hobart."
An Asterisk server also runs on the Aurora Australis supply ship as it braves its way across the Southern Ocean, the VoIP server interfaced with InmarSat and Iridium satellite phones to allow calls throughout the ship. The system uses least cost routing to take advantage of cheaper call rates between phones on the same satellite network.
After evaluating several VoIP solutions, the AAD opted for Asterisk because its open source nature makes it easier to support from afar. It was also easier to integrate with complicated links such as an international E1 circuit, something AAD found difficult using proprietary VoIP solutions. Asterisk also allowed them to easily add extra features such as a PIN system to keep track of each researcher's calls.
"Anything we do in Antarctica we have to be able to support ourselves.
We have two technicians at each station for the year, handling all the radio, phone and IT work - because it's a long way to come for a support call," Yates says.
"Asterisk appeared to have the most potential. As it was an open system, we were able to take the code which drove something the E1 circuit and modify it to meet our requirements. Using open source means we can customise our phone system to meet our specific needs, knowing we can support it ourselves where ever in the world we are."
This was first published in December 2007