Nortel BCM 3.7, Manual

Page: 209 / 1004

Creating numbering plans 209
Programming Operations Guide
Outgoing calls
Outgoing calls require line pool access codes or destination code (with defined routes) to leave the
system.
• Access codes provide direct, unscheduled access to an analog, digital (T1), of Voice over IP
(VoIP) line pool. Refer to
“Programming access codes” on page 321 .
• Destination codes also provide access to line pools, but they also allow more flexibility in
dialing, which allows for more complex routing options, such as scheduling, fallback routing
(VoIP trunks), call definition, and multiple routing (least-cost routing). Routing also allows
you to minimize the dialout for the user, especially to systems on the same private network.
Refer to
“Configuring call routing” on page 331 .
Outgoing calls can be either public or private, which is defined by the route. The public or private
designation determines which dialing plan is used to determine the validity of the call. Normally,
public calls are routed over PSTN trunks and private calls are routed over a private network.
However, MCDN trunks can also pass calls designated as public to allow remote nodes on the
network to call out of the PSTN of a local node. This is called tandem dialing. Refer to
“Outgoing
private calls routing” on page 316 , “Outgoing public calls routing” on page 318 and “Using the
MCDN access codes (tandem calls)” on page 327 .
• If the outgoing call is designated as private, the system checks the beginning of the string for a
destination code that routes to a private network. It also checks that the dial string is the correct
length. The destination code routing determines what the final dial out string will be, adding or
removing digits, as required.
• If the outgoing call is designated as public, the system checks the beginning of the string for a
destination code that routes to a PSTN or an MCDN trunk. If the call routes to a public route,
the system checks the public dialing table to ensure that the dialout string has legitimate
leading digits and is the correct length. If the call routes to an MCDN trunk, the call is passed
as dialed, minus the private networking codes. The call will pass through the system until the
system with the matching destination code receives it, at which point it will be sent through the
local PSTN of that system.