Quick overview from the supplier:
Grandstream UCM6302 IP PBX, 1000 Users, 150 concurrent calls, 2хFXS, 2xFXO, 1xWAN, 1xLAN
//
Supports up to 3000 users and up to 450 concurrent calls
Zero configuration provisioning of Grandstream SIP endpoints
Built-in conferencing & meetings platform; supports desktop, Wave app, and SIP endpoints
Wave for Android, iOS, Chrome and Firefox browsers allows communication with all UCM6300 users & solutions
API available for third-party integrations, including CRM and PMS platforms
Advanced security protection with secure boot, unique certificate and random default password to protect calls and accounts
Three Gigabit auto-sensing RJ45 network ports with integrated PoE+ and support NAT router
Automated NAT firewall traversal service facilitates secure remote connections
Supports Full-Band Opus voice codec and H.264/H.263/ H.263+/H.265/VP8 video codec, jitter resilience up to 50% packet loss
Compatible with GDMS for cloud setup, management and monitoring
Based on Asterisk* version 16 open source telephony operating system
https://www.grandstream.com/products/ip-pbxs/ucm-series-ip-pbxs/product/ucm6300-series-ip-pbx
