Nortel Networks 553-3001-211 manual Distant end disconnect restrictions

Page 54 of 894 Overview

Distant end disconnect restrictions

If the SAL feature is not available in the CS 1000 Release 4.0 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.

553-3001-211 Standard 2.00 September 2004