Yeastar P560 PBX 100user 30channels, Basic features. Upgradeable The Yeastar P560 VoIP PBX is an adaptive, professional, reliable PBX phone system for SMEs. It allows businesses to have uninterrupted communications in at all times in a fully-fledged system. Users 100 / 200, Max Concurrent Calls 30 / 60, Max Call Centre Agents 100 / 200, Max FXS Ports 8, Max BRI Ports 8, Max GSM/4G Ports 4, Max E1/T1/J1 Ports, Expandable D30.