Nortel Networks 311 Voice frequency audio level

42 Overview

Lineside T1 card has operational limitations compared to typical ground

start interface equipment relating to start of dialing, distant end disconnect

and glare potential.

Distant end disconnect restrictions If the SAL feature is not available

in the CS 1000 software, the Lineside T1 card is not capable ofindicating

to the Customer Premise Equipment (CPE) when a call is terminated by

the distant end. In this case, the Lineside T1 card continues 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 provides 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 provides 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 simultaneouslywith the call or iginationattempt

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 trafﬁcvolume and ringing generator

capacity overload, the Lineside T1 ground start operation cannot connect

the tip side to ground to indicate the line has beenseized 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 completes 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.

Voice frequency audio level

The digital pad for Lineside T1 card audio level is ﬁxed for all types of

call connection (0 dB insertion loss in both directions), and differs from

the analog line. Audio level adjustments, if required, must be made in the

Lineside T1 terminal equipment.

Nortel Communication Server 1000

Circuit Card Reference

NN43001-311 01.04 Standard

Release 5.0 23May 2008