Cisco 3600 Series Multiservice Platforms

Understanding Digital Modem Network Modules on Cisco 3600 and 3700 Series Routers

Document ID: 7234

Updated: Jun 21, 2005



The digital modem network modules significantly enhance the dial access flexibility and scalability of the Cisco 3600 platform series. Each network module supports up to 30 digital modems. The digital modem network modules use either the single or dual T1/E1 network modules to offer support for up to 60 remote modem users (using two NM-DM network modules), at speeds up to 56 Kbps.




There are no specific requirements for this document.

Components Used

The information in this document is based on digital modem network modules using either the single or dual T1/E1 network modules.

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.


For more information on document conventions, refer to the Cisco Technical Tips Conventions.

Product Numbers

Here is a table listing the network module product numbers:

Product Number Description
NM-6DM Network Module with six Digital Modems installed
NM-12DM Network Module with 12 Digital Modems installed
NM-18DM Network Module with 18 Digital Modems installed
NM-24DM Network Module with 24 Digital Modems installed
NM-30DM Network Module with 30 Digital Modems installed
MICA-6MOD= Modem Card with six Modems
MMTL-3600-6 Advanced Modem Management Technology License Six Ports1
MMTL-3600-12 Advanced Modem Management Technology License 12 Ports1
MMTL-3600-18 Advanced Modem Management Technology License 18 Ports1
MMTL-3600-24 Advanced Modem Management Technology License 24 Ports1
MMTL-3600-30 Advanced Modem Management Technology License 30 Ports1

1 - Requires Cisco IOS® software plus feature set.


  • Includes up to 30 modems in increments of six.

  • Supported on the Cisco 3620 with Cisco IOS Version 11.3(4)T1 and later, and on the Fast Ethernet plus T1 Network Modules, or Fast Ethernet Plus E1 Network Modules.

  • Field upgraded in increments of six using MICA-6MOD= (same as 6DM=).

  • Uses the same MICA modems as AS5300 (Note: cannot use the 12 port module).

  • Takes analog data calls from T1s, E1s, and Integrated Services Digital Network (ISDN) Basic Rate Interfaces (BRIs) (from BRI network modules, not BRI WAN interface cards [WICs]) and routes them to the modems.

For more details, refer to the Data Sheet.

Feature Support

The table below lists the available features and the software required to support the features.

Feature Software Required
Support for ISDN BRI voice calls Cisco IOS Versions 12.0(2)XC, 12.0(3)T and later
56k flex MICA firmware 2.2 and later
V.90 MICA firmware and Cisco IOS Versions 11.2(16)P or 11.3(5)T and later
Dial-out, fax modem MICA firmware and Cisco IOS Version 11.3(5)T and later
T1 CAS signaling (channelized T1) Cisco IOS Version 11.3(3)T and later
R2 signaling (channelized E1) Cisco IOS Version 12.0(1)T and later
V.110 Cisco IOS Version 12.1(5)T and later

Platform Support

The table below lists the different platforms and the Cisco IOS software versions which support the network modules.

Product Name Cisco 2600, 2600XM, and 2691 Cisco 3620 Cisco 3631 Cisco 3640 Cisco 3660 Cisco 3725 and 3745
NM-6DM, NM-12DM, NM-18DM, NM-24DM, NM-30DM Not supported Cisco IOS Versions 11.3(4)T1, 12.0T, 12.0XK, 12.1, 12.1T, 12.2, and 12.2T Not supported Cisco IOS Versions 11.2(9)XA, 11.2(10)P, 11.3(2)T, and all 12.x Cisco IOS Versions 12.0(7)XK, 12.1T, 12.2, and 12.2T All Cisco IOS software versions

Note: NM-DM modules are not supported in Cisco IOS Version 12.0 on the Cisco 3620. You must use Cisco IOS Version 12.0T or later.

On-line Insertion and Removal (hot swap) requires Cisco IOS Version 12.1(1)T (supported only on 3660 and 3700 platforms).


On the digital modem network modules, the interfaces are addressed as interface async (line number).

Line Numbers

Older versions of Cisco IOS software reserved 16 async line numbers per network module slot. However, when the NM-16A, NM-32A, or digital modems are installed in the Cisco 3600 series, Cisco IOS software will reserve 32 line numbers per slot. This will cause a problem if the NM-16A, NM-32A, or digital modems are installed into a system that already has an async configuration based on 16 line numbers per slot. The aux port will now be line 65 on the Cisco 3620 and line 129 on the Cisco 3640. Use the show line command to check the line numbering on the chassis.

line number = (<slot> * 32) + <unit> + 1

Refer to How Async Lines are Numbered in Cisco 3600 Series Routers for more information.

For a sample configuration, refer to Configuring Modem Connectivity with a Cisco 3640 BRI or Configuring and Managing Integrated Modems. This configuration can be applied to any router with this digital modem network module.

Firmware Upgrade

Refer to MICA Recommended Portware Version and Upgrading the Modem Firmware/Portware in Cisco Routers with Internal Digital Modems for the recommended modem portware version as well as the modem upgrade procedure.

Field Notices

The Field Notices below provide additional information on network modules:

Field Upgrade with MICA-6MOD Modules

Inserting the MICA-6MOD= upgrade into a Digital Modem Network Module




Related Information

Updated: Jun 21, 2005
Document ID: 7234