Nortel BCM50 2.0, Руководство по установке

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Chapter 5 ISDN overview 31
Telephony Device Installation Guide
• Layer 3: Also a logical connection between the ISDN network (your service provider) and the
BCM50 system. For BRI lines, layer 3 is where call processing and service profile identifier
(SPID) information is exchanged. This controls which central office services are available to
the connection. For example, a network connection can be programmed to carry data calls.
These three layers are important when you are installing, maintaining, and troubleshooting an
ISDN system.
ISDN bearer capability
Bearer capability describes the transmission standard used by the BRI or PRI line so that it can
work within a larger ISDN hardware and software network.
The bearer capability for BRI and PRI is voice/speech, 3.1 kHz audio (fax), and data (unrestricted
64 kb/s, restricted 64 kb/s, or 56 kb/s).
Services and features for ISDN BRI and PRI
As part of an ISDN digital network, your system supports enhanced capabilities and features,
including:
• faster call set up and tear down
• high quality voice transmission
• dial-up Internet and local area network (LAN) access
• video transmission
• network name display
• name and number blocking (PRI, BRI and analog)
• access to public protocols
Refer to the following for additional information on features and services:
• “Network name display” on page 33
• “Name and number blocking” on page 33
• “Call by Call Service Selection for PRI” on page 34
• “Emergency 911 dialing” on page 34
• “Two-way DID” on page 35
• “Dialing plan and PRI” on page 35
Note: Throughout this chapter, references are made to Service profile
identifiers (SPIDs). SPIDs are a part of the BRI National ISDN standard.
SPIDs are not used in the ETSI BRI standard or on PRI.