Nortel BCM 3.7, Manual

Page: 873 / 1004

ISDN Programming 873
Programming Operations Guide
Program Direct Inward System Access (DISA) on PRI Lines
(North America)
When a DTM is configured for PRI, all lines on that module are set to Auto Answer without
DISA. DISA, however, can be accessed by one of two methods.
Method 1
Define the DISA DN to match the trailing digits of the Called Party Number (CDN).
With Public, Private, and Tie service types, the CDN is simply truncated to the Target Line
Receive Digit Length and is parsed to match the Target Line Receive Digits. DISA can be
accessed by having the DISA DN match the trailing digits of the CDN. For example, with a
Receive Digit Length = 4, and DISA DN = 1234, a call made to Public DN 763-1234 will be
handled as follows:
• the ISDN setup message will contain a CDN of 763-1234
• the CDN will be truncated to the 4 digits, 1234
• 1234 matches the DISA DN
• the call will be answered with DISA
Method 2 (North America only)
Use incoming Call by Call (CbC) Service routing to map the call type to the DISA DN. Refer
to
“Configuring call routing” on page 331 for more information.
With FX, INWATS, 900, and SDS service types, either a Service Id (SID) or a CDN is mapped
to Target Line Receive Digits. This is programmed under
“Configuring Call by Call services”
on page 350 . DISA may be accessed by having the SID or CDN map to the DISA DN. This
example has a Receive Digit Length = 4, DISA DN = 1234, and CbC Routing with (Service
Type = FX, Map from SID = 2, Map to digits = 1234).
A call presented to the Business Communications Manager system with service type FX and
SID 2 will be handled as follows:
• The ISDN setup message will specify FX with SID = 2
• The FX SID = 2 will be mapped to DISA DN digits 1234
The call will be answered with DISA.