Cisco WAN Interface Cards

Understanding the 1-Port T1 CSU/DSU WAN Interface Card (WIC-1DSU-T1)

Document ID: 7255

Updated: Jan 17, 2007



The T1 Data Service Unit/Channel Service Unit (DSU/CSU) WAN Interface Card (WIC) is an integrated, fully managed DSU/CSU for T1 or fractional T1 service. Cisco 1600, 1700, 2600 and 3600 series routers support the T1 CSU/DSU WIC, which provides a cost-effective router-DSU/CSU combination with these benefits of integration:

  • Fewer devices and cables to deploy and manage

  • Remote and local configuration, monitoring, and troubleshooting through the Cisco IOS® Command Line Interface (CLI)

  • Flexibility and investment protection

  • Single-vendor support

  • Enhanced reliability

  • Physical space savings




There are no specific requirements for this document.

Components Used

This document is not restricted to specific software and hardware versions.


Refer to Cisco Technical Tips Conventions for more information on document conventions.

Product Numbers



The T1 CSU/DSU WIC provides full or fractional T1 service. T1 CSU/DSU WIC does not do channelized T1 or ISDN Primary Rate Interface (PRI).

Refer to the WIC1-DSU-T1 Data Sheet for further details.

Platform Support

Platform Cisco 1600 Cisco 1700 Cisco 2600 Cisco 2600XM Cisco 3620 Cisco 3640 Cisco 3631 Cisco 3660 Cisco 2691 Cisco 3725 Cisco 3745
Cisco IOS Support Cisco IOS Software Releases 11.2(12)P, 11.3(3)T, all 12.x All Cisco IOS Software Releases Cisco IOS versions 11.3(4)T, all 12.x All Cisco IOS Software Releases Cisco IOS Software Releases 11.2(12)P,11.3(3)T, all 12.x Not Supported All Cisco IOS Software Releases Cisco IOS Software Release 12.2(13)T, 12.2(11)YT

Note: The service-module t1 fdl command is available on Cisco 2600 routers in Cisco IOS Software Releases 12.0(3), 12.0(3)S, 11.3(8)T, and 12.0(3)T.

Note: The Cisco IOS software releases provided are typically the minimum version necessary to support the platform, module, or feature in question. Use the Software Advisor to choose appropriate software for your network device: match software features to Cisco IOS and CatOS releases, compare IOS releases, or find out which software releases support your hardware. Use the Software Advisor (registered customers only) and other tools available online.

Sample Configuration

Here is a sample configuration for a WIC-1DSU-T1 interface card. There are no controller or controller-related commands, such as channel-group to configure. This WIC uses service-module commands. The syntax with regard to the framing, line-code, and others remains the same. In addition, the Cisco IOS configuration for this WIC is the same as that for the Cisco 2524 Router. Refer to Configuring Cisco Integrated Data Service Unit/Channel Service Unit (DSU/CSU) Modules and WAN Interface Cards for more information on the commands that you can use.

Note: Here are the differences in the configuration of the WIC-1DSU-T1 from the 2524 router:

  • Does not implement V.54 loop codes (until Cisco IOS Software Release 12.0(3)T).

  • Facilities Data Link (FDL) is off by default. You can configure FDL to either the American National Standards Institute (ANSI) or AT&T 54016, but not both at the same time.

This scenario uses a full T1 card with 24 timeslots:

Interface serial 0/0
service-module t1 clock source internal
service-module t1 timeslots 1-24 speed 64                 
service-module t1 framing esf
service-module t1 linecode b8zs
ip address
encapsulation ppp
no shut

Related Information

Updated: Jan 17, 2007
Document ID: 7255