The Model 272 Telecom
Interface with Smart Disconnect is designed to allow equipment ports
intended for connection to ground start trunk circuits to be interfaced
with loop start trunk circuits. Examples of equipment that can benefit
from the Model 272’s capabilities include PBX, automatic call
distributor (ACD), and voice mail systems. The loop start trunk circuits
that need to be interfaced are typically provided as standard central
office (CO) loop start trunks or off-premise extensions (referred to as
OPS or OPX circuits) from a PBX system. The unit provides four
independent conversion circuits. The Model 272 is intended to be
installed at the customer premises, adjacent to the equipment containing
the ground start trunk ports.
Model 272 features include
LED status indicators, universal powering, and simple installation.
Power and individual circuit active LEDs are provided. The Model 272 can
be powered with 24 Vac, –24 Vdc, or –48 Vdc. There are no switches to
set or straps to cut. The Model 272 automatically adjusts for the power
that is connected. The unit is completely self-contained in a
wall-mounted cabinet. Interconnections are made using a standard 25-pair
telephone-type plug. This method provides simple, time-efficient
installation and maintenance.
The Model 272 Telecom
Interface with Smart Disconnect is intended to serve as a useful
“building block” for special applications. A typical application is to
allow the interfacing of PBX off-premise extensions to a voice mail or
ACD system. It is common for this scenario to arise as often voice mail
and ACD systems are compatible only with ground start trunk circuits.
Another common application arises when linking one PBX to another PBX.
One PBX provides off-premise extensions while the other PBX only has
ground start trunk ports available.
The Model 272 is designed
to allow equipment ports intended for connection to ground start trunks
to be used with loop start trunk circuits. Model 272 circuits cannot be
connected to give the opposite function. If you need to connect loop
start equipment ports to ground start trunk circuits, use the Gordon
Kapes, Inc. GS-1 Loop Start to Ground Start Converter.
Model 272 Specifications
Number of Conversion Circuits: 4
Ringing Voltage: 60-150 Vac, 16-68 Hz
Ringing Detect Time: 100 milliseconds
Circuit Release after Ringing Time: 6
Minimum Ring Load Current: 12 mA
Loop Current Detect Time: 10 milliseconds
Loop Current Disconnect Time: 375
Maximum Loop Resistance: limited by loop
start trunk loop limit
Environment: 0 to 50 degrees C, humidity to
95% (no condensation)
Registration Number: BVV8VH-19259-OT-N
Ringer Equivalence: 1.0 B
Radiated Noise Compliance: contains no
circuitry subject to EMI regulations
Reliability: MTBF 27.8 years, per Method 1 of Bellcore TS-TSY-000332, Issue 3,
Interconnections: one 25-pair plug;
installer must supply one cable terminated with 25-pair connector
Power Requirement: 18 to 30 Vac, 100 mA
maximum Class 2 power transformer only, minimum 5 VA rating –22 to –56
Vdc, 75 mA maximum
8.75 inches high (22.2 cm)
8.75 inches wide (22.2 cm)
3.25 inches deep (8.3 cm)
Mounting: wall mounts with four #8 pan-head
Weight: approximately 2 pounds (0.9 kg)
Specifications subject to change without notice.