T1 Trunk (D4 Ds-1); Figure 18: T1 Trunk Synchronization - Mitel SX-200 EL Technician's Handbook

T1 Trunk (D4 DS-1)

A T1 Trunk is a digital trunking standard that supports multiple users.
Unlike analog trunks, the T-1 hardware signaling layer is independent
of trunk usage; synchronization & signaling are dealt with separately.

Figure 18: T1 Trunk Synchronization

Synchronization
The T1 trunk establishes and maintains a connection between the
two systems. Sampling clocks of each partner must be
synchronized.
The Master-Slave arrangement defines the leader and follower;
n
if connecting to a Public Network T1, the PBX will always be a
slave.
The stratum clock levels define the accuracy of the clock and the
n
ability to match with the incoming master clock signal.The higher
stratum number synchronizes to the same or lower stratum
number. For example, a Stratum 4 (PBX) clock synchronizes to
a Stratum 3 (CO/PBX/Channel Service Unit) clock.
When the PBX is connecting to more than one T-1 signal,
n
choose the order of preference of clocking sources in CDE Form
Troubleshooting and Repair
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