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Port Sizing
November 2004
Avaya Modular Messaging Concepts and
Planning Guide
12-25
ports required will be higher. Planners must take this point into
account when estimating the number of ports required.
! With some switch integrations, such as QSIG and H.323-based IP
integration, each time the Automated Attendant or a Caller
Application transfers an answered call, two ports are utilized.
Therefore, when used often, these interfaces increase port usage.
! Calculation of port usage for MWI varies depending on the
switch integration that the Modular Messaging system and the
switch support. For IP H.323 integration, QSIG, or digital set
emulation switch integrations, administrators are required to
configure port groups for MWI.
! Port usage varies depending on the medium used to access
messages.
— When subscribers use the TUI to retrieve messages, port
usage is high.
— When subscribers access messages from a desktop PC, and
play or record messages using the multimedia capabilities of
the PC, port usage is low.
— When using Client Add-in for Microsoft Outlook to access
messages, if clients play or record messages using a
telephone, port usage is high.
— When using Client Add-in for Microsoft Outlook to access
messages, if clients play or record messages on the PC, port
usage is low.
— When subscribers use the Modular Messaging Web Client or
the UCC Speech Access client for accessing messages,
Modular Messaging port usage is lowered.
! When subscriber use the TUI to retrieve e-mail messages, TTS
resources are in use and the average duration of a call, also
known as the average hold time (AHT) increases. With an
increase in AHT, ports are busy for a longer time.
Total estimated port
requirements
For sizing port requirements:
1. Calculate the total estimated traffic generated by incoming and
outgoing calls
2. Refer to the tables in Appendix A, Grade of service,
for the
number of ports required for a given grade of service.
— If the telephone system does not support queuing of calls, see
the calculations based on the Erlang B model.