Cause value 81

Last Updated : Oct 15, 2014 |
[0x51/0xD1]

Invalid call reference value

Cause

The equipment sending this cause value receives a message with a call reference value that is not currently in use on this user-network (D-channel) interface. This could indicate a call state mismatch for the attempted connection between the two sides of the interface.

This cause value is most often generated when a message in a call clearing sequence of messages is lost in transmission due to problems experienced on the D-channel. One end of the interface treats the call as disconnected, but the other end sends messages to connect the call. The response to this new call clearing sequence becomes a RELEASE_COMPLETE message with Cause value 81.

This cause value has local significance only. The ISDN network between the user and the equipment generating the cause value sends:

  • A no-cause indication through the network

  • A more generic cause value through the network