Mitel Inter-Tel 5000, Installation And Maintenance Manual

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Chapter 4: Specifications
Single and Dual T1/E1/PRI Modules
Page 4-26
Inter-Tel
®
5000 Installation Manual – Issue 2.4, May 2008
Digital information is transmitted over the T1 span as a series of 1s and 0s (e.g., 1000 0000
0000 0001...). If the stream of digits contains too many consecutive zeroes, the T1 clock
extraction circuitry will not operate correctly. To prevent this situation, T1 carrier equipment limits
the number of consecutive zeros. The Inter-Tel system supports the two major types of zero
code suppression schemes in use today: Alternate Mark Inversion (AMI), also called bit-7
stuffing, and Bipolar Eight Zero Substitution (B8ZS). Again, for voice transmissions, AMI is
adequate. However, for 64 Kbps clear channel
data only transmissions, B8ZS is required.
Like the LBO attenuation, the framing scheme type and zero code suppression scheme type
are also available from the T1 provider. In fact, when ordering a T1 span, always request the
following information from the T1 provider:
•
Framing scheme : D4 Superframe or ESF
•
Zero code suppression scheme : AMI or B8ZS
•
Recommended line build-out attenuation : 0 dB, 7.5 dB, 15 dB, or 22.5 dB
Each T1 port has circuitry to support up to 24 T1 span channels. The channels (or circuits) can
be any combination of loop start trunks, ground start trunks, DID trunks, E&M trunks, or OPX
circuits.
The T1M and T1M-2 modules are equipped with the following resources:
•
LED indicators : Show the status of the module and circuits and to show T1 trunk alarms
and module-level error occurrences. For additional information about LEDs, see the
Diagnostics and Troubleshooting chapter in the
Inter-Tel 5000 Features and Programming
Guide (part no. 580.8006).
•
Digital span jack : (RJ-48C; 8-pin, 8-conductor jack) Connects a T1, T1/PRI, E1/PRI span
to the module. The T1M is equipped with one RJ-48C jack for the span and another RJ-
48C jack to connect test equipment to monitor the span. The T1M-2 is also equipped with
two RJ-48C jacks; however, both jacks are used for individual spans. The T1M-2 has no
RJ-48C jack for test equipment.
•
DTMF transmitters : (T1M and T1M-2 modules only) Generates DTMF tones for traffic on
the T1M and T1M-2 modules. To use these transmitters, the Enable On-Module Dialing
flag must be enabled in DB Programming. Refer to the Inter-Tel 5000 Features and
Programming Guide (part no. 580.8006).
Programming information that is specific to each T1/PRI installed in the system. For details,
refer to the Inter-Tel 5000 Features and Programming Guide (part no. 580.8006):
•
Framing type : The type of framing scheme, D4 Superframe or Extended Superframe
(ESF), used by the T1 span connected to each module.
NOTE
The T1M and T1M-2 module DTMF transmitters are not shared resources.
Only the T1M and T1M-2 modules can use these transmitters.
IMPORTANT
DB Programming will display an error message under the following
circumstances:
•
Change the port type of one port if the other port is programmed
(not None).
•
Change the Framing Type under a T1 port and the other port is
programmed (not None). This field also exists under the T1/PRI
port type, but it is OLM only.
DB Programming displays: WARNING: Changes to this field are only
recommended on an idle system as this may cause a short pause in
audio on the other port of this module (but no dropped calls). Would
you like to continue?