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Level 10
Level 10

Core Issue

The error message displayed in the ISDN Q.931 translator is similar to this:

ETUP pd = 8 callref = 0x0049
  Bearer Capability i = 0x8090A2
  Channel ID i = 0xA98397
  Calling Party Number i = 0x0081, '9203'
  Called Party Number i = 0x80, '3308'
RELEASE_COMP pd = 8 callref = 0xC9

  Cause i = 0x81B6 - Incoming calls are barred

This problem arises if the user's setup is configured to use PriDmsSetupMsg (PRI DMS-100) but Cisco CallManager uses the existing gateway flag MCDN Channel Number Extension Bit Set to Zero to control the channel extension bit for all normal call    setup messages and restart/service maintenance messages.


In order to get the DMS-100 to work with Cisco CallManager 4.1(3), the user needs to enable MCDN Channel Number Extension Bit Set to Zero and Interface Identifier Present.

Check MCDN Channel Number Extension Bit Set to Zero in the Cisco 6608 configuration on Cisco CallManager, then update and reset. The calls should work now.

When the PRI ISDN switch type is DMS-100 for an MGCP-controlled gateway off of the Cisco CallManager, the DMS-100 protocol can either have a 4-byte or 2-byte CALLREF value. This is the only protocol that does this. By default, the CALLREF value on the Cisco CallManager is 4 bytes long (for example, CALLREF = 0X0000).

Complete these steps under the gateway page on Cisco CallManager when the protocol requires a 2-byte CALLREF value:

  1. Set the ISDN switch type to PRI DMS-100.
  2. Check MCDN Channel Number Extension Bit Set to Zero.
  3. Check Interface Identifier Present.

    This setting only applies to the DMS-100 protocol for digital access gateways in the Channel Identification information element (IE) of the SETUP, CALL PROCEEDING, ALERTING, and CONNECT  messages.

    This Interface Identifier value needs to stay at 0.

This problem is also documented in Cisco bug ID CSCdv86713 - Restart Bit for DMS-100 incorrectly set.

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