Features • Meets or Exceeds All AT&T D3/D4 Specifications and CCITT Recommendations • Complete CODEC and Filtering Systems: No External Components for Sample-and-Hold and Auto-Zero Functions. Receive Output Filter with (SIN X)/X Correction and Additional 8kHz Suppression • Variable Data Clocks - From 64kHz . . . . . . . . . . . . . . . . . . . . . 2.1MHz • Receiver Includes Power-Up Click Filter • TTL or CMOS-Compatible Logic • ESD Protection on All Inputs and Outputs