Connecting Multiple Devices to an ISDN Line
If you do not plan to connect anything except a single PC
ISDN adapter to your ISDN line, you can ignore this section.
It is possible to connect up to eight devices to a single
ISDN line. These devices can include network routers and bridges,
Group 4 ISDN fax machines, ISDN telephones as well as traditional
analog telephone devices. ISDN is intelligent enough to arbitrate
the use of the two B channels between these devices (up to
two devices can be in use simultaneously) and route incoming
calls to the appropriate device.
Instead of connecting the ISDN line to a single PC, it is
possible to connect an ISDN line to a LAN so all the PCs on
the LAN can share the ISDN line. This requires an ISDN network
bridge or router.
It is possible to connect several ISDN devices to a single
ISDN line. For example, you might wish to have an ISDN adapter
in your PC, an ISDN telephone to make voice calls and a Group
4 ISDN fax machine all connected to the same ISDN line. Incoming
data calls would go to the PC, voice calls to the telephone
and fax calls to fax machine. To support this configuration,
you need an NT-1 that supports multiple S/T Interface connections.
Each device would be connected to the NT-1. Each device would
also need its own Service Profile Identifier (SPID) to ensure
the telephone company can route calls to the appropriate device.
In addition to ISDN devices, some NT-1s or ISDN adapters
also support analog telephone devices like phones, data modems,
Group 3 fax machines and answering machines. The NT-1 or the
ISDN adapter converts the analog signal into ISDN and vice
----- picture ------