Mitel SX-200 EL Technician's Handbook page 92

Technician's Handbook
44, T1 Network Sync (always choose a connection as close as
possible to the defined master source clock).
Signaling Types
Channel Associated Signaling
The original idea behind the T1 is to emulate 24 independent analog
trunks. The Channel Associated signaling supports Loop Start,
Ground Start, DID/Loop, and E&M trunks. The function of each
channel is decided and programmed at each end.
All handshake signaling is done with bits (A&B) stolen from the bit
stream; used to emulate the various analog signals, (offhook,
onhook, current reversal, etc.) and is used as the equivalent to that
of the analog trunks.
Because A&B bits are taken from the bit stream, this signaling
method is not appropriate for direct transmission of digital
information unless it is modulated into an analog signal with a
modem.
Common Channel Signaling
The Handshake signaling for the first 23 channels is managed by
the 24th channel. The Common Channel signaling allows for
transmission of digital information and more advanced digital trunk
applications (MITEL's MSDN, Bell Canada's Megalink, ISDN, etc.).
Signaling protocol is defined by the type of service.
Test/Verify (T1)
Synchronization
Most T1 issues are a result of connectivity problems.
n
Verify that the incoming T1 signal is seen at both ends; verify all
hardware connections. Failure at either end indicates loss of an
incoming synchronizing signal.
Verify that the switch settings on the T1 card are set for proper
operation. For example: 1 is closed and 2-8 are open.
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