Severn Trent has recovered £3m in unpaid bills in the last 12 months through the use of voice messaging technology.
The water utility firm used software from Qire, known as interactive voice messaging, to automatically call people that owe it money.
Severn Trent uses the system to recover funds from accounts that have been closed but not yet paid up.
The system dials the bill payer and after confirming their identity transfers them to an agent without charging them.
The system has sent 176,000 messages to customers in arrears since it was deployed in September and has recovered £3m. The use of the system has also increased the value of repayments customers are making.
"As well as recovering millions in overdue bill payments, the payments we are now receiving are on average more than 30% higher than those previously achieved through traditional contact methods such as through dialler-based calling or postal campaigns," said Russell Mackuin, debt strategy and controls manager at Severn Trent.
One of the main benefits of the software is that it provides a cost-free call for the customer, which was welcomed by regulators and customer support groups.