4,8,12,16 FXS/FXO ports PCI card Asterisk, FreeSwitch, Elastix Detecttion of busy tone, DTMF, FSK Adjustable line gain ... PCI/PCI-E analog card for Freeswitch and Asterisksupport ... On Demand5, Voice Mail Services6, Call Centers7, Prepaid Calling Card System8, Callback Service9, Traditional Calls/VoIP Calls Conference Hardware ...