Used Cisco WAN ISDN Network Module

Part # NM-2T1-CSU

Product Description: Cisco 3600, 3700 Series -  2-Port Channelized T1/ISDN-PRI with CSU Network Module.

About the Cisco 3700 Series: "Modular routers, targeted at branch offices. Supports Frame Relay, ISDN, LL, X.25, ATM, fractional T1/E1, xDSL, T3/E3, HSSI WAN protocols" (Cisco A Beginner's Guide Third Edition by Velte & Velte).

Cisco 3600 WAN ISDN Network Modules
Cisco 3700 WAN ISDN Network Modules
Cisco Routers - Part Numbers Listed Alphabetically