User manual

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OLUTION ARCHITECTURE

5.1.10.12 FTU

At power failure or processor malfunctions, the FTU board connects up

to eight preselected analog phones directly to the public telephone

exchange (PSTN terminals) through analog trunk lines. Normally the

analog phones are connected to the ELU terminals, and the PSTN termi-

nals to TLU terminals on the FTU2 board.

5.1.10.13 VCU

The Voice Compression Unit is used for the Dynamic Route Allocation

feature. The VCU application on the SPU4 can handle two timeslots with

four compressed channels each. Each channel can either be decom-

pressed or switched to another timeslot. The VCU is not available for

new sales.

5.1.10.14 LSU-E

The LIM Switch is a distributed function that handles the TDM switching

function through the back-plane. It consists of five boards, one LSU-E,

and four DSUs, for a 1024 x 1024 timeslot switch. The LSU-E communi-

cates with the telephony applications running on the server through an

Ethernet interface. Internally, the LIM Switch consists of a control

memory and a speech memory. The control memory stores the connec-

tion information while the speech memory stores speech samples.

The LIM Switch is also able to attenuate or amplify the audio sample that

is switched through. Sixteen alternative levels are accessible in the

LSU-E or DSU for A-law coding and there are also a number of defined

levels for mu-law coding. The different alternative levels are market

dependent. For more information, see the appropriate market character-

istics documentation. The LSU-E is also equipped with a clock unit that

has hold-over capabilities. Hold-over means that the external synchroni-

zation frequency can be memorized and synchronization maintained

even if the external synchronization is lost for a short while. The LSU-E

and DSU take synchronization from one selected device board. Each of

the DSUs serves 256 timeslots and performs serial and parallel

con-version of the Pulse Code Modulation (PCM) signals to and from the

device boards.

This board is only used for migration of Stackable systems.

5.1.10.15 IPLU

The IPLU board handles rtp-resources, and media connections between

or to the IPLU and a terminal (SIP or H.323). It supports up to 32 concur-

rent media channels. The IPLU has two external interface connectors on

the board front, one Ethernet port and one RS232-port for debugging