Cisco 3600 Series Multiservice Platforms

Field Notice: Using Digital Modems with the Cisco 3600 Basic Rate Interface (BRI) Network Module Upgrade

Updated April 19, 2002

December 3, 1998

Products Affected




Four-port ISDN BRI network module


Four-port ISDN BRI with integrated NT-1 network module


Eight-port ISDN BRI network module


Eight-port ISDN BRI with integrated NT-1 network module

Problem Description

The ISDN BRI network modules for the Cisco 3600 require a minimum version in order to be used with the following digital modem network modules:

  • NM-6DM

  • NM-12DM

  • NM-18DM

  • NM-24DM

  • NM-30DM

If you do not plan to use the ISDN BRI network module with digital modems, this minimum version is not required. If you use an ISDN BRI network module without the minimum required version in a Cisco 3600 system with digital modems, an error message similar to this will appear when the router boots:

The MBRI network module in slot 0 is incompatible with 
the digital modems installed in the router.

Problem Symptoms

Modem calls on an ISDN BRI B channel which will not work with digital modems.


Cisco IOS releases 12.0(2)XC and 12.0(3)T have a new feature that allows modem calls on an ISDN BRI B channel from an ISDN BRI network module to be sent to a digital modem network module. However, there is a minimum hardware level required for the BRI network module to support this feature. The WIC-1B-S/T and WIC-1B-U cannot send modem calls to the digital modem network module.


The required minimum version for modem calls via the ISDN BRI network module appears below:


Minimum Version









The version of the ISDN BRI network module appears in the Part Number field from the show diag command. Here is an example:

BRI (U) port adapter, 0 ports
Port adapter is analyzed
Port adapter insertion time unknown
Hardware revision 0.0           Board revision A0
Serial number     0             Part number    800-01239-03
Test history      0x0           RMA number     00-00-00
EEPROM format version 0
EEPROM contents (hex):
    0x20: 00 23 00 00 00 00 00 00 50 04 D7 03 00 00 00 00
    0x30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

Released Product Change Notice (RCN)

RCN number: R98-1687 36XX: Release Upgraded PROM for 4/8 Port ISDN-BRI Network Modules

Upgrade Program

If you need a BRI network module upgrade, please submit a return materials authorization (RMA) through the Technical Assistance Center (TAC).

For More Information

If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods: