Central Yeastar S100 The Yeastar S100 VoIP PBX is specially designed for small and medium businesses, supporting up to 100 users. Features of Yeastar S100 Call Transfer Database CRM Call Recording Conference Calls IVR Tree Real-time Reports and Analytics Yeastar S100 Central Specifications Designed specifically for small, large and medium businesses. Supports 100 users (expandable to 200). Supports 30 simultaneous calls (expandable to 60). It has 16 FXS/ FXO/ BRI ports. Supports 6 GSM/ CDMA/ 3G/ 4G mobile lines.