Nortel Circuit Card, Installation Manual, Page: 56 / 908

Page 56 of 906 Overview
553-3001-211 Standard 3.00 August 2005
Distant end disconnect restrictions
If the SAL feature is not available in the CS 1000 Release 4.5 software, the
lineside T1 card is not capable of indicating to the Customer Premise
Equipment (CPE) when a call has been terminated by the distant end. In this
case, the lineside T1 card will continue to provide a grounded tip indication
(A=0) to the CPE until it detects an open loop indication (A=0) from the CPE,
at which time it will provide an open tip indication (A=1). Therefore, without
SAL software, the lineside T1 card is not capable of initiating the termination
of a call to the CPE.
With the SAL software configured for each lineside T1 line, the lineside T1
card will provide an open tip indication to the CPE when it receives an
indication of supervised analog line from the system. This provides normal
ground start protocol call termination.
Glare restrictions
In telephone lines or trunks, glare occurs when a call origination attempt
results in the answering of a terminating call that is being presented by the far
end simultaneously with the call origination attempt by the near end.
The lineside T1 detects presentation of a terminating call (outgoing to lineside
T1 terminal equipment) by detecting ringing voltage. If application of the
ringing voltage is delayed due to traffic volume and ringing generator
capacity overload, the lineside T1 ground start operation cannot connect the
tip side to ground to indicate the line has been seized by the system.
In ground start mode, glare conditions need to be considered if both incoming
and outgoing calls to the Customer Premise Equipment (CPE) are going to be
encountered. If the system and the CPE simultaneously attempt to use a
lineside T1 line, the system will complete the call termination. It does not
back down and allow the CPE to complete the call origination, as in normal
ground start operation.
If both incoming and outgoing calls are to be handled through the lineside T1
interface, separate channels should be configured in the system and the CPE
for each call direction. This eliminates the possibility of glare conditions on
call origination.