The company replaced BT voice systems with technology from Avaya to improve the handling of customer queries.
Stephen Boulton, head of IT at Leek United Building Society, said the company had to improve the level of customer service it provided.
"We could not route people properly to the people with the right skills," he said.
Previously the head office had 100 analogue telephones, which have been replaced with a digital phone on every desk. When a customer calls, all the information required can be made available to the call-centre worker, depending on what product the customer is calling about.
Staff were trained to use the system a week before the system went live.
The company is considering rolling out the technology to its 11 other sites.