The Cisco NM-1A-T3/E3 (related family to NM-1A-T3/E3 and variants such as NM-1T3/E3) is a single-port WAN network module designed for Cisco Integrated Services Routers (ISR). It provides carrier-class T3 (DS3) or E3 connectivity, allowing routers to connect directly to high-speed telecom WAN circuits.

This module supports clear-channel and subrate T3/E3 transmission, eliminating the need for external CSU/DSU devices and enabling direct termination of leased lines.

It is commonly used in enterprise WAN aggregation, service provider edge networks, and legacy high-bandwidth leased-line deployments.

Key Features

1 × T3/E3 WAN interface port
Software-configurable for T3 (DS3) or E3 operation
Supports clear-channel and subrate transmission
Integrated line interface unit (no external DSU required)
Uses 75-ohm BNC coaxial connectors (TX/RX)
Supports high-speed WAN leased lines
Compatible with multiple Cisco ISR platforms (2600/2800/3800 series depending on IOS)
Provides carrier-grade WAN termination
Supports ATM or packet-over-T3/E3 variants (depending on model)

Technical Specifications

Part Number: NM-1A-T3/E3 (and variants such as NM-1T3/E3 depending on platform)
Product Type: WAN Network Module
Interface: 1 × T3/E3 port
Line Rate:
- T3 (DS3): 44.736 Mbps
- E3: 34.368 Mbps
Connector Type: Dual 75-ohm BNC (TX/RX)
Framing: C-bit, M13 (T3), G.751 (E3)
Encoding: B3ZS (T3), HDB3 (E3)
Interface Type: WAN leased line termination
Platform Support: Cisco ISR 2600/2800/3800 series (varies by IOS version)
Form Factor: Single-wide Network Module (NM slot)
Use Case: WAN backbone, carrier interconnect, legacy leased-line circuits