A.the analog phone will be connected to the FXS port， and the fax machine will be connected to the FXO port on router R1
B.the analog phone will be connected to the FXO port， and the fax machine will be connected to the FXS port on router R1
C.both devices will be connected to the FXS port on router R1
D.both devices will be connected to the FXO port on router R1
E.both devices will be connected to the E and M ports on router R1

A.voice gateways with analog interfaces need a gatekeeper to convert analog signals into digital format before voice is encapsulated into IP packets
B.voice gateways need a gatekeeper to interconnect the VoIP networks the PSTN network
C.voice gateways with Cisco Unified CallManager Express （CME） can permanently act as a call agent for IP phones
D.voice gateways equipped with a DSP module can take the role of the call agent during WAN failure.