... Detecttion of busy tone, DTMF, FSK Adjustable line gain PCI/PCI-E analog card for Freeswitch and Asterisksupport 4 to 16 FXS/FXO ... , VoIP Services3, VoIP Gateways4, FAX Server, FAX On Demand5, Voice Mail Services6, Call Centers7, Prepaid Calling Card System8, Callback Service9, Traditional Calls ...