Nortel Communication Server 1000S Installation And Configuration Manual page 335

Note: For CS 1000S, the NTAK79 card and NTBK50 cards are installed
only in the MG 1000S. They are not supported in the MG 1000S
Expansion.
Each MG 1000S that has a digital trunk must have a clock controller set
Note: Clocking slips can occur between MG 1000S systems that are
clocked from different COs, if the COs are not synchronized. The slips
can degrade voice quality.
The NTBK50 supports the following clock controller and D-channel handler
daughterboards:
• NTAK20 clock controller daughterboard
• NTAK93 D-channel handler daughterboard, or NTBK51 Downloadable
D-channel daughterboard.
If the NTAK93 D-channel daughterboard is attached, the NTBK50 PRI card
functions in the same manner as the NTAK79 PRI card. If the NTBK51
D-channel daughterboard is attached, software is downloaded to the card
instead of residing in a D-channel circuit.
For information on the NTBK50 faceplate LEDs, refer to ISDN Primary Rate
Interface: Maintenance (553-3001-517).
NTAK20 Clock Controller (CC) daughterboard
The NTAK20 Clock Controller daughterboard is used with the NTBK50
2.0 Mb PRI card. The NTAK79 PRI card has an on-board clock controller.
2.0 Mb PRI implementation
IMPORTANT!
to an external reference clock.
ISDN Primary Rate Interface
Page 335 of 394
Installation and Configuration