Cisco VIC3-2FXS/DID, Two-Port Voice Interface Card- FXS and DID.
FXS port is used to connect directly to phones, fax machines, and key systems. Generates battery polarity reversal and caller ID.
DID port is used to provide off-premises DID connection from central office. Serves only incoming calls from the PSTN. Does not support caller ID in DID mode.