One customer told Fairfax Media his internet connection dropped out nearly two weeks ago, but he was unable to phone the company.

Graham Edwards he had tried calling “at least 50 times” but received an engaged signal.

A third party website, Product Review, includes pages of complaints from customers with internet outages and difficulties contacting Southern Phone.

Managing director David Joss said an influx of new business overwhelmed the phone system, leading to customers constantly getting a busy signal.

He said it would be a further two weeks before a new phone system was installed and recommended customers contact the company via the chat line on their website.

Mr Joss said Southern Phone has increased its NBN business.

“There’s a change in customer behaviour on the back of the NBN services, where they typically ring us a lot more and those calls have overwhelmed our phone system essentially,” Mr Joss said.

Mr Joss said the problems with the existing phone system were realised a week and a half ago and an upgrade was begun.

“These things are complex,” he said.

“We’re working towards it as fast as we possibly can.”

The managing director said there was a notification of the phone problems on the Southern Phone website but a recent upgrade caused it to disappear.

A notification was placed on the site on Wednesday night and a letter had been sent to customers.

“We absolutely acknowledge the inconvenience to our customers and we apologise for that,” he said.