Audio Only 1000 Users, 4 FXO, 4 FXS Based on Asterisk* version 16 open-source telephony operating system Zero configuration provisioning of Grandstream SIP endpoints Built-in Instant Messaging (IM), Audio Conferencing & Web Meetings platform that supports access from computers, mobile devices, and SIP endpoints Free Wave App allows easy voice & Instant Messaging (IM) communications using desktops, Web, and Android/ iOS devices 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 Compatible with GDMS for cloud setup, management, and monitoring