Mitel 3300 ICP Hardware User's Manual page 187

The two external FIM connections are for providing connectivity to NSUs.
Note: You may need to add a DSP resource to upgrade the 100 User System with any
of the following: 30 Voice Mail Ports, Peripheral cabinet, NSU, 6500 Speech Enabled
Applications. See your Mitel Networks Sales Engineer for more information.
Note that there are two T1/E1 links per NSU.
250 User System - Add Voice Mail Ports
250 user system (Release 3.0/3.1 chassis) upgrade to add support for 30 voice mail ports.
This system uses the following existing modules:
• One 300 MHz RTC
• One 300 MHz E2T
• One 64 Channel Echo Canceller
• One Dual FIM
• One DSP Module (21061/21161) for telecom support
Add the following module:
• One DSP Module (21161) for 30 Voice Mail Ports
This provides:
• 4 DSP devices (21061/21161) for telecom functions for up to 250 users
• 30 Voice Mail Ports
• 64 Channels of Echo Cancellation
• 2 External FIM connections
• Four ASU connections (CIM ports)
The four external FIM connections are for providing connectivity for up to four Peripheral Units
or up to eight NSUs.
Release 3.3
Install Upgrades and FRUs
179