Based on this product's specifications, here are some alternatives and similar models
VoIP Gateway Yeastar D30 — supports 100 users, 30 concurrent calls
Summary description:
Yeastar D30 is a VoIP gateway designed for small and medium business telephony. It supports up to 100 users and handles 30 concurrent calls, enabling SIP trunking and PBX integration. The device is intended for routing voice over IP traffic, consolidating phone lines, and improving call capacity and reliability for office environments and remote sites.