update Problems with Telstra's new Siebel-based billing system have led to call centres being choked by long delays and errors, according to one of the telco's unions. However, Telstra claimed the union had attempted to undermine the IT transformation's success.

The Community and Public Sector Union (CPSU) today claimed the three-month-old Siebel system was faulty and placed intolerable pressure on call centre workers to meet performance targets.

The system is believed to have been implemented with help from IT services giant Accenture over the past several years. Siebel is now owned by former rival Oracle.

The union said a survey of hundreds of Telstra workers showed that 96 per cent believed the IT system was to blame for loss of business, while 86 per cent said they were held responsible for the system's failures.

CPSU national president Louise Perrse said Telstra chief executive Sol Trujillo and his managers were blaming staff for a fall in business.

"Trujillo's so-called IT transformation has run over schedule and over budget and the Telstra boss has clearly introduced his system before it was ready, creating massive problems for call centre workers and their customers," she said.

Perrse said that rather than take the blame for the faulty system, Trujillo was punishing call centre workers for falling customer business.

"An unworkable IT system has meant that many Telstra workers are struggling to meet their targets — targets they are forced to meet to make up their take-home pay," Perrse said.

David Moffatt, group managing director for Telstra's consumer division, admitted in an email that the telco's IT transformation was going through its toughest period, but insisted that the project was a success, despite the union's attempts to paint it in a bad light.

"Without doubt this is the period that is toughest, because we are embedding a new system and people have been working across the old and the new," he said.

"Telstra is unconcerned by this latest union attempt to undermine the success of the IT transformation. The results outlined in detail at Telstra's investor day last week demonstrate beyond doubt that the IT transformation is on track."

"We are working very closely with our employees to help them implement the new systems and they are delivering," he added, pointing out that the new system was handling 6.3 million customers and 11 million services.

In contrast, the CPSU's survey showed that 13 per cent of staff believed their Siebel training was adequate.

"We think the reality of millions of successful transactions speaks a lot louder than the union's survey sample," Moffat rebutted.

ZDNet.com.au's Renai LeMay contributed to this article.