Nortel Passport 15000 Preparation Manual page 86

86 Chapter 2 Planning considerations
241-1501-205 5.2S2
If the timing source of your site is BITS, you must provide and install
whatever timing cables are needed to connect the site source to the
alarm/BITS module itself on the Passport 15000 or 20000, or to a cable
assembly that is connected to the alarm/BITS module.
For information on installing or replacing the timing cables, refer to
241-1501-240 Passport 15000, 20000 Hardware Installation, Maintenance
and Upgrade.