Cisco EM-HDA-6FXO High-Density Analog 6-Port FXO Power Failover Voice Fax Expansion Module

The Cisco EM-HDA-6FXO gives an EVM-HD-8FXS/DID baseboard six FXO ports that reach the central office over off-premises analog voice and fax lines. Beside the EM-HDA-3FXS/4FXO, which divides seven ports between FXS and FXO, this module puts all six of its ports on the FXO side. If the router loses power, FXO power failover can open a direct path between an FXO port and an analog phone, so a line to the PSTN stays available. Any port also supports analog CAMA, short for Centralized Automated Message Accounting. The ports use loop start or ground start signaling, and dialed digits can travel in-band as DTMF or out-of-band as 10 pps pulses. Disconnect supervision responds to a power interrupt over 600 ms, a progress tone below 600 Hz or a battery polarity reversal. The module has no connector of its own, so its ports come out on the baseboard's RJ-21 connector, and up to two expansion modules fit on each baseboard. With one of these modules the baseboard reaches 14 voice sessions, with two it reaches 20, and PVDM2 modules bought separately supply the DSP resources.