7 dtu-t1 cas – Nortel Networks DCT1900 User Manual

Page 45

Technical Product Manual - DCT1900

System Description, Radio Exchange Boards

System-DCT1900/R8/mw

4-7

4.7

Digital Trunk Unit - DTU-T1 CAS (REX-BRD0021 or 2/ROFNB 157 13/2)

DTU T1 CAS is used only in Standalone configurations. The DTU provides the digital interface
between the PBX and the RE. The physical connection with the PBX is established via 100 ohm
twisted pair cables.

Every DTU board contains 2 DTCs (see Figure 4-6), each equipped with identical firmware. Both
DTCs support the Channel Associated Signalling (CAS) interface.

Each CAS interface provides 24 (total 48 per board), communication channels to which Portable
Telephones are assigned individually. Each channel is dedicated to a specific Portable Telephone
number. The maximum number of Portable Telephones a RE can handle is 600. This is
supported on 13 DTU T1 CAS cards.

Fig. 4-6 DTU-T1 CAS

DTC2

DTC1

Channels

25 - 48

Channels

1 - 24

1.544 Mbit/s

Trunk

1.544 Mbit/s

Trunk