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18 September 2007
SYSTEM DESCRIPTION, INSTALLATION, AND MAINTENANCE MANUAL
eNfusion™ HSD-128 High-speed Data Terminal
Connect to the HSD transceiver’s Ethernet interface either directly from a 
dedicated Ethernet card using an Ethernet crossover cable or from a hub using 
a regular Ethernet cable.
B. Mapping User Devices for ISDN Services
This section describes how the HSD system manages ISDN traffic for user devices 
connected to the network.
(1) Overview
HSD transceivers support connection to a multitude of user devices allowing the user 
to customize their system. Because each user’s equipment setup is unique, the HSD 
system uses routing codes to ensure that incoming calls (whether data or voice) reach 
the appropriate device. These same routing codes also direct outgoing calls to the 
appropriate Swift64 service type supported by the Inmarsat Satellite Communications 
Network (3.1 kHz Audio, 64 kbps Speech, 64 kbps Data, 56 kbps Data, or in 
Stand-Alone systems—4.8 kbps LSV).
The physical interface for ISDN service is EURO S/T, which supports several types 
of connections to user equipment. HSD transceivers provide either one or two ISDN 
S/T (BRI) Bus interfaces (depending on the number of channel cards and mode of 
installation of the unit).
Each bus is capable of hosting up to eight, EURO ISDN physical devices—which 
means a one-channel system supports up to eight physical connections to EURO 
ISDN devices; whereas, a two-channel system supports up to sixteen physical 
connections to EURO ISDN devices. 
Note:
An HSD transceiver with a DATA I/O Card Type 2 (models 1110-A-0150 and 
1110-A-0160 or units with service bulletin 1110-SB-0004 accomplished) also 
supports eight devices per channel card, but uses one “device connection” 
on the first channel card for system use, therefore providing up to fifteen 
possible device connections in two-channel systems. 
Each channel card provides one, 64 kbps ISDN B channel that is available to either 
ISDN Bus. If the channel(s) is “busy” or “in-call”, the request for service is denied (the 
system is busy).
For ISDN data devices that support bonding (with a two-channel card, HSD 
transceiver), the device will attempt to use both ISDN B channels to increase data 
throughput (as long as no other devices are “in call”).
For incoming calls, each channel card (ISDN BUS) is assigned a Forward ID. The 
Forward IDs are assigned Inmarsat Mobile Numbers (IMNs) for each service type. 
Two service types are assigned multiple IMNs; 64 kbps data is assigned three IMNs 
and 4.8 kbps LSV is assigned 16 IMNs.
Note:
Sixteen MSNs for 4.8 kbps LSV were implemented in Version 4.1 Control 
Card Software. Systems shipped from the factory after November 15, 2002 
have Version 4.1 software or later.
Each service type IMN has associated Multiple Subscriber Number (MSN). MSNs are 
used to configure the user devices so that incoming calls of different service types 
are routed to the appropriate device.