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Specifications
INTER-TEL
®
AXXESS
®
MANUAL VERSION 11.0 – May 2008
Voice Channel Allocations
SPECIFICATIONS
2
Voice Channel Allocations
4.17 The circuitry and software in each single equipment chassis combine to produce an
“integrated switching matrix” of 128 time slots (4 PCM highways [buses] × 32 time slots per
highway). A quad-chassis system has 512 time slots (16 PCM highways [buses] × 32 time slots
per highway). In general, the circuit cards in slots one and two are assigned to highway one,
the cards in slots three and four are assigned to highway two, and so on. Therefore, there are at
least 16 time slots available for each card installed in the chassis.
NOTE: The ATM connection to the chassis in a tri-/quad-chassis configuration provides 256
time slots for communication between the two halves (8 channels × 32 time slots per channel).
Of the 256 times slots, 224 are available as non-blocking voice channels. All of the DSP
resources on the CPU020 cards, OPCs, and DKSC-16s can be shared across the fiber-optic
connection.
4.18 For the most part, having 16 time slots available per card presents no problem. For
example, each Digital Keyset Card (DKSC), whether equipped with any Single-Line Adapters
or not, requires 16 time slots. Each Loop/Ground Start Card (LGC) and each Loop Start Card
(LSC) requires four time slots. (If equipped with Daughter Cards, LGCs and LSCs require
eight time slots.) And, each Single-Line Card (SLC) or 16-Port Single-Line Card (SLC-16)
requires eight or sixteen time slots respectively.
4.19 Some cards could require more than 16 time slots. For example, each Options Card
(OPC) and each BRI card (BRS or BRU) could possibly need more than 16 time slots, depend-
ing on the number of Digital Signal Processors (DSPs) installed on the card. With a U.S. sys-
tem, each T1 Card (T1C) and each T1/PRI card and each T1/E1/PRI card could require up to
24 time slots. With a European system, each E1/PRI Card and each T1/E1/PRI Card could
require up to 30 time slots. And, each 16-Port Digital Keyset Card (DKSC-16) could require
up to 32 time slots.
4.20 To reduce the chance of T1C, T1/PRI, E1/PRI, T1/E1/PRI, OPC, BRS, BRU, and
DKSC-16 circuit blocking, the time slots for these types of cards are allocated dynamically
(e.g., they are allocated as needed). In addition, since T1Cs, T1/PRIs, E1/PRIs, T1/E1/PRIs,
OPCs, BRS, BRU, and DKSC-16s can use unused time slots from any highway in its respec-
tive equipment chassis, the chance of any optional DSP resource or circuit being blocked is
extremely remote and can be prevented (see the following note). Therefore, the phone system
is considered to be a virtually non-blocking system.
NOTE: If multiple OPCs, T1Cs, T1/PRIs, E1/PRIs, T1/E1/PRIs, BRSs, BRUs, and/or DKSC-
16s are installed in expanded chassis, resource blocking can be prevented by splitting the cards
between the cardfiles and/or installing them in the same cardfile as the LGCs or LSCs. In tri-/
quad-chassis installations, the master T1C, E1/PRI card, or T1/E1/PRI card (if one exists)
should be located in the master dual-chassis.
4.21 The following chart shows the number of voice channels that are used by the various
cards. Note that dynamically allocated voice channels are not used until they are needed.
Table 2-1. Maximum Voice Channels for Various Cards
Card Max. Voice Channels Used
E1C 30 – Dynamically Allocated
T1C 24 – Dynamically Allocated
T1/PRI 23 – Dynamically Allocated
E1/PRI 30 – Dynamically Allocated
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