This document describes one reason why CPU usage for Cisco Unity goes
up to more than 90% when Cisco Unity performs Message Waiting Indicator (MWI)
dial-out to the Cisco CallManager Express. This document also provides a
solution in a Cisco CallManager Express and Cisco Unity environment.
Cisco recommends that you have knowledge of these topics:
The information in this document is based on these software and
Cisco CallManager Express version 3.3
Cisco Unity version 4.0(5)
Cisco IOS Software Release 12.3(14)T5
The information in this document was created from the devices in a
specific lab environment. All of the devices used in this document started with
a cleared (default) configuration. If your network is live, make sure that you
understand the potential impact of any command.
Technical Tips Conventions for more information on document
The MinimumMWIRequestInterval parameter is the minimum time between
MWIs. It controls the rate at which outgoing serial packets are sent to the
phone system. An MWI request frequency under heavy load can cause MWI failure.
The MinimumMWIRequestInterval setting works as a switch file parameter to
control the rate at which MWIs are sent to the phone system. The setting can
prevent MWI failures. By default, this setting is disabled.
After an upgrade to Cisco Unity 4.0(5), two problems start on Cisco
MWI does not function for some users.
CPU usage for Cisco Unity reaches more than 90%. In order to reduce
CPU usage, the only method is to kill the AvNotifierMgr service (see arrow A in
However, Cisco Unity users can still perform these tasks:
Figure 1:AvNotifierMgr Service
The solution is to add this text to the Cisco0002.ini file which is
located in the \CommServer\InitLib\ folder (see arrow A in Figure 2):
Figure 2: Cisco0002.ini
This forces Cisco Unity to wait to dial out the MWI and prevents the
MWI from causing looping and collisions.