What best describes an FXO interface?()
A、analog trunks that provide the Survivable Remote Site Telephony (SRST) feature
B、analog trunks that provide VoIP gateway functionality
C、analog trunks that connect a gateway to plain old telephone service (POTS) device such as analog phones, fax machines, and legacy voice-mail systems
D、analog trunks that connect a gateway to a central office (CO) or private branch exchange (PBX)