... of busy tone, DTMF, FSK Adjustable line gain PCI/PCI-E analog card for Freeswitch and Asterisksupport 4 to 16 FXS/FXO ... FAX On Demand5, Voice Mail Services6, Call Centers7, Prepaid Calling Card System8, Callback Service9, Traditional Calls/VoIP Calls Conference Hardware and ... software requirements: 1, Interface: PCI 2.22, CPU 800+MHZ3, RAM 128+MB4, Linux ...