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Walkthrough Wednesdays

The isdn bind-l3 ccm-manager command for PRI is not detected, nor displayed, in the Cisco IOS MGCP gateway configuration


Core Issue

The isdn bind-l3 ccm-manager command backhauls (tunnels) ISDN Layer 3 (L3) and higher layers to the Cisco CallManager. PRI/Q.931 signaling backhauls signals (Q.931 and higher) for processing from a PRI trunk that physically connects a Media Gateway Control Protocol (MGCP) gateway to a MGCP call agent. The ISDN lower layer information (Q.921 and lower) terminates and is processed on the gateway. The L3 information (Q.931 and higher) is transported over TCP to the Cisco CallManager (MGCP call agent).

This problem is discussed in Cisco bug ID CSCed15644.


To resolve this issue, perform one or more of these steps:

  • Reload the gateway.    

  • Manually add the isdn bind-l3 ccm-manager command to the gateway configuration.    

  • If the ccm-manager config command is configured, remove it from the configuration and set the missing command (isdn bind-l3 ccm-manager) under the serial interface. Then, save this configuration to the Nonvolatile RAM (NVRAM), and reload.  
Krisztian Papp


I tried to use this isdn bind-l3 ccm-manager command in our voice gw (2811, IOS 12.4(15)T8 with VWIC2-2MFT-T1/E1), but under "interface Serial0/0/0:15" I could not issue it. Only "isdn bind-l3 q931" is the available option. I checked IOS and feature (MGCP PRI Backhaul and PRI/Q.931 Signaling Backhaul) compatibility with Software Advisor, but it tells this IOS is fine (min support: 12.4(2)T3). Do you have any idea why this command could not be used?

Lukasz Swidzinski
Cisco Employee

Maybe this will help other facing same issue

service mgcp  is necessary under T1 or E1 controller config

pri-group timeslots 1-3,24 service mgcp