Telos TWOx12 - Mixed Isdn;Analog Configurations

TELOS TWOX12 USER’S MANUAL
INSTALLATION
CHAPTER 2 27
h
HOT TIP!
A few years back we always advised that hybrid performance was best when equipment
was connected directly to the lines from the Telco. Today, this is not always true. If the PBX
is connected to the Telco using digital lines (such as T1, E1, PRI, S2, etc), performance
through a digital PBX will generally be better than direct connections to copper analog
circuits. This is particularly if you are located a significant distance from the Telco central
office.
The biggest variable when connecting to a PBX analog port is the quality of the analog port.
We have found that many PBX manufacturers offer more than one analog port option. The
better port can usually be distinguished by its higher cost, and the fact that it may offer 48
volts rather than 24 volts. The Telos TWOx12 will work with either voltage, however
experience has shown that the 48 volt version usually has better quality transformers and
other components resulting in better hybrid performance.
The other thing to investigate is whether the PBX offers "Loop Current Drop" or "CPC"
(Calling Party Control) on its analog ports. Without this supervision the TWOx12 will not
be able to determine If a party on hold has hung up, and your talent will get a recording
"please hand up and dial again…" or dial tone when attempting to air the call.
2.5.4 Mixed ISDN/Analog Configurations
Those who desire a system with mixed analog and ISDN connections may replace one of
the interface cards with one of the other type. Section 8.6 lists the part numbers for the
interface cards.
The TWO x12 has been designed to work in the following mixed configurations:
A) 1 Analog interface (slot A) and 2 ISDN interfaces (slots B & C) for a total of 11 lines:
A mixed interface TWOx12 with a POTS interface card in slot A and ISDN interface cards in slots
B, & C. The POTS interface supports 3 circuits while the ISDN interface supports two ISDN BRI
circuits. Since each BRI has two Telco channels (or “Lines”) there are 4 channels per BRI
interface card. This configuration has a total of 11 channels.