Cause Code Mappings

The tables below display the mappings of Cause Codes to Request Failure response

ISUP Q.931 Cause Code to SIP Request Failure Response Codes

ISUP Cause Value

SIP Response

Normal event

1 – unallocated number

404 Not Found

2 – no route to network

404 Not Found

3 – no route to destination

404 Not Found

16 – normal call clearing

--- (*)

17 – user busy

486 Busy here

18 – no user responding

408 Request Timeout

19 – no answer from the user

480 Temporarily unavailable

20 – subscriber absent

480 Temporarily unavailable

21 – call rejected

403 Forbidden (+)

22 – number changed (s/o diagnostic)

410 Gone

23 – redirection to new destination

410 Gone

26 – non-selected user clearing

404 Not Found (=)

27 – destination out of order

502 Bad Gateway

28 – address incomplete

484 Address incomplete

29 – facility rejected

510 Not implemented

31 – normal unspecified

480 Temporarily unavailable

34 – no circuit available

503 Service unavailable

38 – network out of order

503 Service unavailable

41 – temporary failure

503 Service unavailable

42 – switching equipment congestion

503 Service unavailable

47 – resource unavailable

503 Service unavailable

55 – incoming calls barred within CUG

403 Forbidden

57 – bearer capability not authorized

403 Forbidden

58 – bearer capability not presently available

503 Service unavailable

65 – bearer capability not implemented

488 Not Acceptable here

70 – Only restricted digital information bearer capability is available (National use)

488 Not Acceptable here

79 – service or option not implemented

501 Not implemented

Invalid message

 

87 – user not member of CUG

403 Forbidden

88 – incompatible destination

503 Service unavailable

102 – Call Setup Time-out Failure

504 Gateway timeout

111 – Protocol Error  Unspecified

500 Server internal error Interworking

127 – Internal Error - interworking unspecified

500 Server internal error

 

(*) ISDN Cause 16 will usually result in a BYE or CANCEL

(+) If the cause location is user then the 6xx code could be given rather than the 4xx code. the cause value received in the H.225.0 message is unknown in ISUP, the unspecified cause value of the class is sent.

(=) ANSI procedure

 

SIP Request Failure Response Codes to ISUP Q.931 Cause Code

Response received Cause value in the REL.

SIP Status Code

ISDN Map

400

Bad Request 41 – Temporary failure

401

Unauthorized 21 – Call rejected (*)

402

Payment required 21 – Call rejected

403

Forbidden 21 – Call rejected

404

Not Found 1   – Unallocated number

405 Method not allowed 63 –  Service or option unavailable
406 Not acceptable 79 – Service/option not implemented (+)
407 Proxy authentication required 21 – Call rejected (*)
408 Request timeout 102 – Recovery on timer expiry
410 Gone 22  –  Number changed (w/o diagnostic)
413 Request Entity too long 127 – Interworking (+)
414 Request –URI too long 127 – Interworking (+)
415 Unsupported media type 79 – Service/option not implemented (+)
416 Unsupported URI Scheme 127 – Interworking (+)
402 Bad extension 127 – Interworking (+)
421 Extension Required 127 – Interworking (+)
423 Interval Too Brief 127 – Interworking (+)
480 Temporarily unavailable 18 – No user responding
481 Call/Transaction Does not Exist 41 – Temporary Failure
482 Loop Detected 25 – Exchange – routing error
483 Too many hops 25 – Exchange – routing error
484 Address incomplete 28 – Invalid Number Format (+)
485 Ambiguous 1 – Unallocated number
486 Busy here 17 – User Busy
487 Request Terminated --- (no mapping)
488 Not Acceptable here --- by warning header
500 Server internal error 41 – Temporary Failure
501 Not implemented 79 – Not implemented, unspecified
502 Bad gateway 38 – Network out of order
503 Service unavailable 41 – Temporary Failure
504 Service time-out 102 – Recovery on timer expiry
505 Version Not supported 127 – Interworking (+)
513 Message Too Large 127 – Interworking (+)
600 Busy everywhere 17 – User busy
603 Decline 21 – Call rejected
604 Does not exist anywhere 1 – Unallocated number
606 Not acceptable --- by warning header
  

H.225 Release Reason to Q.931 Cause Code Mapping

The table below displays the mappings of the H.225 Release reason to Q.931 Cause Codes. If the cause value received in the H.225 message is unknown in ISUP, the unspecified cause value of the class is sent.

Note: If an H.323 endpoint rejected the call with just a H.225 release reason as displayed in the table below, the 2020 IMG would only see the ISUP cause code and that’s what would be sent to the cause code table.

H.225 Release reason ISUP Cause Codes
invalid CID 3 - No route to destination
unreachableDestination 3 - No route to destination
facilityCallDetection 16 – Normal call clearing
destinationRejection 16 – Normal call clearing
inConf 17 – User busy
calledPartyNotRegistered 20 – Subscriber absent
badFormatAddress 28 – Invalid number format
undefinedReason 31 – Normal, unspecified
securityDenied 31 – Normal, unspecified
callerNotRegistered 31 – Normal, unspecified
replaceWithConferenceInvite 31 – Normal, unspecified
genericDataReason 31 – Normal, unspecified
neededFeatureNotSupported 31 – Normal, unspecified
noBandwidth 34 – no circuit/channel available
unreachableGatekeeper 38 – Network out of order
adaptiveBusy 41 – Temporary failure
gatewayResources 42 – Switching equipment congestion
newConnectionNeeded 47 – Resource unavailable, unspecified
gatekeeperResources 47 – Resource unavailable, unspecified
invalidRevision 88 – Incompatible destination
tunnelledSignallingRejected 127 – Interworking, unspecified
noPermission 127 – Interworking, unspecified
nonStandardReason 127 – Interworking, unspecified