Yeastar SIP Ext.: 300 by default ( max. 500), Concurrent call: 60 by default (max. 120),Expand Cards: max. 3 EX08/ EX30 & 2 D30, Analog Ports: max. 24 FXS/FXO ports,BRI Ports: max. 24 BRI ports, GSM Ports: max. 6 GSM ports,E1/T1 Ports: max. 3 E1/T1 ports, Storage: SD Card / USB / Hard Disk