Based on this product's specifications, here are some alternatives and similar models
VoIP eSBC Patton SmartNode 5600 4 SIP-Calls high performance
Summary description:
The Patton SmartNode 5600 is an enterprise Session Border Controller (eSBC) designed for high-performance VoIP deployments supporting 4 concurrent SIP calls. It provides SIP session control, security and interoperability between networks, and is suited for small branch offices, SIP trunking and service provider edge applications. Benefits include centralized SIP management, improved call reliability and secure interconnection.