it is an DAC (Digital to analogue converter
SDSL- symmetric digital subscriber line
The PRI, or Primary Rate Interface, is a telecommunications level in the IDSN, or Integrated Services Digital Network. It is used to transfer voice to the user.
IDSN BRI, also known as a Two-B-plus-D provides:2 x 64KBps B channels1 x 16 KBps D Channel.IDSN PRI (Primary Rate Interface) in North America provides:23 x 64 Kbps B Channels1 x 64 Kbps D ChannelIDSN PRI in Europe provides:30 x 64 Kbps B Channels1 x 64 Kbps D Channel