Nortel BCM 3.7, Manual

Page: 210 / 1004

210 Creating numbering plans
N0008589 3.3
Incoming calls
Incoming call handling also depends on the call type. The system also uses the Public and Private
DN # length settings to determine call handling. Refer also to
“Defining DN length” on page 294 .
The system processes a call in the following way:
1
The system receives a call from the public or private network.
2 The system identifies the call type:
Public calls:
• If the call is from the MCDN network and is a local, national, or special call type, the
system prepends the appropriate access code.
• If the call is from ETSI-QSIG, MCDN, NI-2, DMS100, DMS250) and tagged as
Private/Subscriber, the system prepends the Private access code, if the dialing plan is UDP.
• If the call is tagged as Unknown/Unknown or Private/Unknown (ETSI-QSIG, MCDN, N1,
DMS100, DMS250 trunks), no access code is added.
• For all other call types, the system truncates the trailing digits to the Public Received #
Length. (Go to step 5)
Private calls:
• If the call is tagged as Private/Subscriber or Private/UDP, the system prepends the Private
access code.
• If the call is tagged as Private/CDP, no access code is added.
3 The system tries to match the first digit(s) of the dial string to a destination code. If the digit(s)
matches, the dial string is routed out of the system.
4 If the system cannot match the first digit(s) to a destination code, it truncates the trailing digits
to the Public Received # length or Private Received # length, as appropriate to the call type.
5 The system again tries to match the leading digit(s) to a destination code. If the digit(s) match,
the dial string is routed out of the system.
6 If the system cannot match the first digit(s) to a destination code, the system tries to match the
dial string to a target line (Public or Private Received Number). If the dial string does not
match any target lines, the call is routed to the prime line.
Refer to the figure below for a graphic illustration of incoming call processing.