问题:
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)
● 参考解析
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