Specifications

Chapter 1 Installation
1-11
Access Bank T1 Network Line can be configured as AMI (Alternate Mark Inversion or Zero Code
Substitution) or B8ZS (Bipolar 8 Zero Substitution) line code format. Line coding options determine the
technique used to handle more than 7 zeros in a row. B8ZS line coding substitutes a Bipolar Violation
after 7 zeros, allowing use of 64 Kbps of each DS0 channel. AMI requires that Bit 8 of each DS0 channel
be "jammed" to a one, yielding only 7 of 8 bits or 56 Kbps of each DS0 for user data. Note that the line
coding mode chosen on the Access Bank Line port must match the T1 carrier's transmission equipment.
On point-to-point customer-owned copper wiring up to 6000 feet, B8ZS line coding is suggested between
Access Banks.
Switch #6 - CSU Loop Code Detection
The CSU Switch is selected as Off to enable standard CSU Loop Codes (either in-band SF or out-band
ESF) to be detected or On to configure the Access Bank to ignore Loop Codes. CSU Switch in the Off
position should be selected (to meet FCC requirements) when connecting the Access Bank directly to a
public carrier T1 line. The CSU Switch must be turned On when operating the Access Bank on the
equipment port or drop and insert T1 port of an external CSU or multiplexer, such as the Carrier Access
DataSplit.
Switch #7 - Test Tone
Used in conjunction with the TP Busy/Idle switch set in the Busy position.
When the Test Tone and TP Busy/Idle switch are both On, an internally generated 1kHz Digital Milliwatt
signal will be received by all 24 channels. This is useful for tone alignment and to isolate transmission
failure problems between the Access Bank and connected switching equipment. This switch should
always be Off for normal Access Bank operation.
!! Note: Please disconnect any telephones before conducting this test!!
Switches #8, 9, & 10
These switches are not used and should be left in the Off position for normal operation.
Self Test Switch
This switch should be in the normal position for normal operation.
Network Loopback Switch
This switch should be in the normal position for normal operation.
Unused Switch
This switch should be in the normal position for normal operation.
Alarm Cut-Off Switch
This switch should be in the normal position for normal operation.