Atreus Systems, a supplier of IP-based voice and advanced IP service provisioning software, is bought by Sonus Networks, located in Massachusetts, for an undisclosed sum. Sonus, which has worked with Atreus for five years, says it acquired the Ottawa-based Atreus to gain expertise in the integration of operating support systems and the provision of IP services for fixed-line and mobile operators’ access networks, including network management systems, billing and customer care systems.