3Com SuperStack 3 NBX Administrator's Manual page 33

Dial Plan Concepts and Overview 33
Hybrid Mode Operation Using the Dial Plan
If you map telephone buttons for some telephones but not others, you
enable Hybrid mode (a mixture of standard and Keyset behaviors). The
system provides a system-wide External Prefix setting, which allows the
administrator to establish a prefix.
Off-Site Notification
The NBX system uses off-site notification to notify users when new voice
mail messages arrive. You can define notification devices and assign them
in the Internal dial plan as well as through the NBX NetSet utility.
Example: When voice mail arrives, the NBX system dials the telephone
number of the user's pager.
Typically, you use a system-wide prefix to designate which device or
devices you want to use for outdialing purposes, including off-site
notification calls.
Example: If the user's pager number is 800-555-3751, and the
system-wide prefix digit is 9, the system dials 98005553751 to send
a call to the user's pager.
To tell the system to dial a single Line Card port or a restricted number of
Line Card ports, create a suitable pool of Line Card ports for that purpose,
and then use an existing set of dial plan table entries (such as the entries
that begin with 8) or create a new set of entries to allow the dial plan
devices to route calls via the selected line card ports.
Example: You set up one 4-port card to handle all off-site notification calls.
You create a set of entries in the Internal dial plan table that each start
with the digit 8. You define a route to the 4-port card for all of these dial
plan entries so that whenever the system acts on one of these entries, it
uses one of the 4 ports on that card to dial out and notify the user.
To apply different off-site CoS restrictions to different users, you need
multiple dial plan entries. If you are not trying to apply the CoS
restrictions, then a single dial plan entry is sufficient.