The Data 56K DDS Locally Powered interface card transmits data over a switched network. It is used to dial out and to answer calls, but instead of sending voice, it sends data at different rates, from 2.4 kbs to 72 kbs.
Both CO and Station side Data 56K DDS Locally Powered interface cards use one transceiver back-to-back with a CPLD (Complex Programmable Logic Device) that does frequency adjustments and acts as a conditioning buffer for the fiber CPLD.
On the fiber side, the signal generated by the transceiver will be encoded on the fiber in the same manner as the T1 interface card, but at a rate that is configurable by a DIP-switch.
Digital Data Service (from 2.4 kbps through 72 kbps, inclusive)
Data 56K DDS Locally Powered Cards