A worker cleans up a Telstra public phone in central Sydney, February 11, 2010. Reuters/Daniel Munoz

A fire in Sydney exchange affected a national Telstra network on Thursday, significantly impacting businesses. Train lines were closed off in New South Wales and flights were delayed as a result of the incident.

The telecom giant said the network was affected due to a fire at the Chatswood Exchange in Sydney. In a social media post shortly before 2:00 p.m. on Thursday, the company said technicians were working on the scene and “completing a full assessment.”

The consequences of the outage have been significant. As reported by AAP (via Yahoo 7), as many as nine Jetstar flights have been delayed as a result of disruptions in check-in ports. The NAB is notifying its customers of delays to SMS alerts.

Commuters on the Hunter Line in New South Wales also faced difficulties due to the network failure. Subsequently, they had to take buses instead. Longer delays were expected.

The fire, which had occurred in Chatswood, had caused damage to the power equipment. At 3:00 p.m., Telstra posted on social media that the services were beginning to be brought back to normalcy. The development came hours after the first reports of problems with the network had emerged.

More issues emerged following Telstra’s announcement, with some customers saying their text messages were being sent to incorrect numbers. There were also complaints from customers receiving text messages from strangers. The affected areas included Canberra, Perth, Brisbane, Melbourne and parts of regional South Australia.

“Cannot call or receive calls from a mobile — great situation for a sales rep,” Steve from Boronia, Victoria said. Another customer, Sarah, from Western Australia, complained she could not call Telstra. “My mobile can receive text messages but I cannot call Telstra or call out,” she said. “My land line is also dead. What is happening. This is my business phone and I’m cut off!”

Last year, a plan of $50 million was announced by Telstra following a series of network meltdowns. The plan involved constructing a more robust network and adding more levels of redundancy to prevent a meltdown.

Speaking to News Corp Australia, CEO Andy Penn said last year it was unpredictable whether the network would suffer meltdowns in the future. “What I can guarantee though is that its absolutely got our full attention and backed up with a significant amount of investment, both in terms of addressing the issues we’ve identified but also building the resiliency and redundancy in the future,” he said.