User's Manual

Dial plan considerations
A uniform dial plan greatly simplifies configuration, management and phone calls within the
network branch sites. For example, if each branch has similar roles such as reception, manager
and warehouse - using the same extension number for each role and a unique prefix for each
branch allows calls between sites with little need for directory lookups. It also means a standard
configuration can be used at branches; simplifying installation, user training and
maintenance.
For our examples we have used the following dial plan for each branch site:
• 3-digit branch prefixes beginning with 8 — A 3-digit branch prefix in the range 800 to
899. This allows us up to 100 branches yet keeps call routing simple. Any dialing at a
branch that being with an 8 can be assumed to be a call to a branch number and can be
routed to the Avaya Aura
®
Session Manager for routing to the correct branch.
• 3-digit extension numbers beginning with 2 — 3-digit extension numbers for all native
extensions and hunt groups starting from 200. This is the default numbering used by
B5800 Branch Gateway.
Centralized survivable extensions may have very different numbering. However, even here,
adopting elements of the uniform dial plan will simplify management and usage. For the
survivable extensions in our examples we have used a dial plan that has 6-digit extension
numbers of which the first 3 digits are equal to the branch prefix. This allows users that migrate
from the Distributed Branch user model to the Centralized Branch user model to keep their
same numbers. The numbers for the survivable extensions can also be different and don’t
necessarily have to share common first digits.
Dial plan example
To describe a dial plan example, we have created Acme Travel, a travel agency with a growing
number of branches. Each branch follows the same pattern, with extensions for a branch
manager and a small team of travel consultants in a sales group.
Given the nature of the business, branch users need to make national and international calls.
The company has taken advantage of a bulk call contracts from it headquarters site so wants
such calls routed via the headquarters site wherever possible. In addition, the branch staff want
to keep their branch phone numbers.
• 3-digit branch numbers beginning with 8, ie. 800 to 899.
• 3-digit native extension numbers beginning with 2, ie. 200 to 299.
Planning
30 Implementing the Avaya B5800 Branch Gateway November 2011
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