AMT/PTD/PBX/0058/4/6/EN Installation and Maintenance Manual - Aastra 5000
Page 228 01/2011 Description des sous-ensembles
4.13.4 LT2 card
4.13.4.1 Description
The LT2 card is a card providing access to the digital network. It provides connection:
• either to the primary rate interface of a European ISDN network (E1, 32 TSs) or a US
type ISDN network (T1, 24 TSs),
• or to PCM digital links channel by channel, which can be used to provide tie line links
with another private installation.
The S2/T2 interface can be configured to supply:
• one connection at reference point S2 to a terminal,
• one connection at reference point T2 to the network
These cards also handle packet-mode data transmission service on channel D between
the network and a terminal.
4.13.4.2 Functional description (see Figure 4.35 )
The LT2 card provides the following functions:
• interface with one ISDN primary rate interface consisting essentially in:
- aligning frames between the internal PCM link TSs and B channels (30 or 23
according to the type: E1 or T1) at 64 kbit/s of a primary ISDN link
- inserting and extracting call status signals over the D channel of the ISDN link,
• PCM line interface (up to 32 channels) consisting mainly of:
- aligning frames between the internal PCM links and the external PCM links,
- inserting and extracting call status signals, PCM channel by PCM channel,
• management of indicators showing the status of frames and calls
• Power supply: the LT2 card also receives on the backplane connector (J1) the +5 V
supply voltage, used for the operation of its internal circuits.
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