Cisco 4 Port Inverse Multiplexing Network Module ATM-T1 4T1-IMACisco ATM T1 4T1 IMA 4 port Inverse Multiplexing Adapter Network Module product information. The NM 4TI IMA is a Cisco network module for Cisco 2600, 3600 and 3700 Series. This 4 port T1 ATM network module with Inverse Multiplexing over ATM (IMA). Supports four T1 E1 ATM ports Support for ATM Forum IMA Version 1. 0 Up to 16 Mbps full duplex bandwidth with an 8 port E1 IMA network module Supports UBR, VBR rt, VBR nrt, and ABR ATM CoS Maximum of four