Specifications

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Cisco IGX 8400 Series Provisioning Guide, Release 9.3.3 and Later Releases
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Chapter 7 Cisco IGX 8400 Series Voice Service
Voice Service—Functional Overview
The UVM extracts information from the CAS signaling bits in the T1, E1, or J1 frame. When a signaling
bit changes state, the UVM sends signaling packets to the card at the other end of the connection. The
UVM can set, invert, and clear AB or ABAB bits (T1 lines) or ABCD bits (E1 or Y1 lines) to allow for
some types of signaling conversion.
Tip To see the signaling configuration, enter the switch software dsplncnf command. To configure the line’s
signaling, enter the switch software cnfln command.
Tip On CCS, E1 or J1 lines, configure channel 16 as a t-type or td-type connection.
Signaling bits are forced to a predetermined state when a transmission link fails, in order to drop calls
in progress and block new access to the voice circuits. Usually, the predetermined state is “idle then
busy,” (idle for a short interval to drop all calls in progress followed by permanent busy until the fault
clears) but other conditioning sequences are allowed.
Tip To condition voice-frequency (VF) signaling—that is, to specify the channel on-hook (idle) state and the
signaling state forced by the CVM or UVM when a connection fails—enter the switch software cnfcond
and cnfvchtp commands. From the options under the cnfvchtp command, select one of the voice
interface types from the screen. If a connection fails, channel voice and signaling conditions are
instantaneously applied.
D-Channel Compression on the UVM
D-channel compression reduces the bandwidth consumed by a CCS signaling channel by eliminating
idle patterns from the data stream. This may reduce the consumed bandwidth by as much as 75 percent.
Tip To enable D-channel compression, add the signaling connection through Cisco WAN Manager or enter
the switch software addcon command, and specify the connection type as “td.” The maximum number
of td connections on a UVM is 32.
Table 7-2 Signaling Formats Supported on the UVM
Line Type Line Framing Signaling Format Signaling Bit
T1 D4 CSS —
T1 ESF CSS —
T1 ESF CAS ABAB
T1 ESF CAS ABCD
T1 D4 CAS AB
E1or Y1 — CAS ABCD
E1or Y1 — CSS —