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The following table lists the Q.850 Cause Codes from the ITU-T Recommendation, Series Q: Switching and Signalling.

Q.850 Cause Codes

Cause Code

Reason

l

Unallocated (unassigned) number.
This cause indicates that the called party cannot be reached recluses although the called party number is in a valid format. It is not currently allocated (assigned).

2

No route to specified transit network (national use)
This cause indicates that the equipment sending this cause has received a request to route the call through a particular transit network which it does not recognize. The equipment sending this cause does not recognize the transit network either because the transit network does not exist or because that particular transit network. While it does exist. does not serve the equipment which is sending this cause.

3

No route to destination
This cause indicates that the called party cannot be reached because the network through which the call has been routed does not serve the destination desired. This cause is supported on a network dependent basis.

4

Send special information tone
This cause indicates that the called party cannot be reached for reasons that are of a long term nature and that the special information tone should be returned to the calling party|

5

Mis-dialed trunk prefix (national use)
This cause indicates the erroneous inclusion of a trunk prefix in the called party number. This number is to sniped from the dialed number being sent to the network by the customer premises equipment.

6

Channel unacceptable
This cause indicates that the channel most recently identified is not acceptable to the sending entity for use in this call.

7

Call awarded. being delivered in an established channel
This cause indicates that the user has been awarded the incoming call and that the incoming call is being connected to a channel already established to that user for similar calls (e.g. packet-mode x.25 virtual calls).

8

Preemption
This cause indicates the call is being preempted.

9

preemption - circuit reserved for reuse
This cause indicates that the call is being preempted and the circuit is reserved for reuse by the preempting exchange.

10

Normal call clearing
This cause indicates that the call is being cleared because one of the users involved in the call has requested that the call be cleared. Under normal situations, the source of this cause is not the network.

14

QoR: ported number
This cause indicates that an exchange detected that the called number was ported out.

17

User busy
This cause is used to indicate that the called party is unable to accept another call because the user busy condition has been encountered. This cause value may be generated by the called user or by the network. In the case of user determined user busy it is noted that the user equipment is compatible with the call.

18

No user responding
This cause is used when a called party does not respond to a call establishment message with either an alerting or connect indication within the prescribed period of time allocated.

19

No answer from user (user alerted)
This cause is used when the called party has been alerted but does not respond with a connect indication within a prescribed period of time. Note This cause is not necessarily generated by Q.931 procedures but may be generated by internal network timers.

20

Subscriber absent
This cause value is used when a mobile station has logged off. radio contact is not obtained with a mobile station or if a personal telecommunication user is temporarily not addressable at any user-network interface.

21

Call rejected
This cause indicates that the equipment sending this cause does not wish to accept this call. although it could have accepted the call because the equipment sending this cause is neither busy nor incompatible. This cause may also be generated by the network, indicating that the call was cleared due to a supplementary service constraint. The diagnostic field may contain additional information about the supplementary service and reason for rejection.

22

Number changed
This cause is returned to a calling party when the called party number indicated by the calling party is no longer assigned. The new called party number may optionally be included in the diagnostic field. If a network does not support this cause, cause no. 1, unallocated (unassigned) number shall be used.

23

Redirection to new destination
This cause is used by a general ISUP protocol mechanism that can be invoked by an exchange that decides that the call should be set-up to a different called number. Such an exchange can invoke a redirection mechanism, by use of this cause value, to request a preceding exchange involved in the call to route the call to the new number.

24

Call rejected due to feature at the destination
This cause indicates that the call has been rejected due to feature at the destination.

25

Exchange – routing error
This cause indicates that the destination indicated by the user cannot be reached, because an intermediate exchange has released the call due to reaching a limit in executing the hop counter procedure. This cause is generated by an intermediate node, which when decrementing the hop counter value, gives the result 0.

26

Non-selected user clearing
This cause indicates that the user has not been awarded the incoming call.

27

Destination out of order
This cause indicates that the destination indicated by the user cannot be reached because the interface to the destination is not functioning correctly. The term "not functioning correctly" indicates that a signal message was unable to be delivered to the remote party; e.g., a physical layer or data link layer failure at the remote party or user equipment off-line.

28

Invalid number format (address incomplete)
This cause indicates that the called party cannot be reached because the called party number is not in a valid format or is not complete.

29

Facilities rejected
This cause is returned when a supplementary service requested by the user cannot be provide by the network.

30

Response to STATUS INQUIRY
This cause is included in the STATUS message when the reason for generating the STATUS message was the prior receipt of a STATUS INQUIRY.

31

Normal. unspecified
This cause is used to report a normal event only when no other cause in the normal class applies.

34

No circuit/channel available
This cause indicates that there is no appropriate circuit/channel presently available to handle the call.

38

Network out of order
This cause indicates that the network is not functioning correctly and that the condition is likely to last a relatively long period of time e.g., immediately re-attempting the call is not likely to be successful.

39

Permanent frame mode connection out-of-service
This cause is included in a STATUS message to indicate that a permanently established frame mode connection is out-of-service (e.g. due to equipment or section failure) (see Annex A/Q.933)

40

Permanent frame mode connection operational
This cause is included in a STATUS message to indicate that a permanently established frame mode connection is operational and capable of carrying user information.

41

Temporary failure
This cause indicates that the network is not functioning correctly and that the condition is no likely to last a long period of time; e.g., the user may wish to try another call attempt almost immediately.

42

Switching equipment congestion
This cause indicates that the switching equipment generating this cause is experiencing a period of high traffic.

43

Access information discarded
This cause indicates that the network could not deliver access information to the remote user as requested. i.e., user-to-user information, low layer compatibility, high layer compatibility or sub-address as indicated in the diagnostic. It is noted that the particular type of access information discarded is optionally included in the diagnostic.

44

Requested circuit/channel not available
This cause is returned when the circuit or channel indicated by the requesting entity cannot be provided by the other side of the interface.

46

Precedence call blocked
This cause indicates that there are no predictable circuits or that the called user is busy with a call of equal or higher preventable level.

47

Resource unavailable, unspecified
This cause is used to report a resource unavailable event only when no other cause in the resource unavailable class applies.

49

Quality of Service not available
This cause is used to report that the requested Quality of Service. as defined in Recommendation X.213. cannot be provided (e.g., throughput of transit delay cannot be supported).

50

Requested facility not subscribed
This cause indicates that the user has requested a supplementary service which is implemented by the equipment which generated this cause but the user is not authorized to use.

53

Outgoing calls barred within CUG
This cause indicates that although the calling party is a member of the CUG for the outgoing CUG call. Outgoing calls are not allowed for this member of the CUG.

55

Incoming calls barred within CUG
This cause indicates that although the calling party is a member of the CUG for the incoming CUG call. Incoming calls are not allowed for this member of the CUG.

57

Bearer capability not authorized
This cause indicates that the user has requested a bearer capability which is implemented by the equipment which generated this cause but the user is not authorized to use.

58

Bearer capability not presently available
This cause indicates that the user has requested a bearer capability which is implemented by the equipment which generated this cause but which is not available at this time.

62

Inconsistency in outgoing information element.
This cause indicates an inconsistency in the designated outgoing access information and subscriber class.

63

Service or option not available. unspecified
This cause is used to report a service or option not available event only when no other cause in the service or option not available class applies.

65

Bearer capability not implemented
This cause indicates that the equipment sending this cause does not support the bearer capability requested.

66

Channel type not implemented
This cause indicates that the equipment sending this cause does not support the channel type requested

69

Requested facility not implemented
This cause indicates that the equipment sending this cause does not support the requested supplementary services.

70

Only restricted digital information bearer capability is available (national use)
This cause indicates that the calling party has requested an unrestricted bearer service but the equipment sending this cause only supports the restricted version of the requested bearer capability.

79

Service or option not implemented unspecified
This cause is used to report a service or option not implemented event only when no other cause in the service or option not implemented class applies.

81

Invalid call reference value
This cause indicates that the equipment sending this cause has received a message with a call reference which is not currently in use on the user-network interface.

82

Identified channel does not exist
This cause indicates that the equipment sending this cause has received a request to use a channel not activated on the interface for a call. For example. if a user has subscribed to those channels on a primary rate interface numbered from l to 12 and the user equipment or the network attempts to use channels l 3 through 23, this cause is generated.

83

A suspended call exists, but this call identity does not
This cause indicates that a call resume has been attempted with a call identity which differs from that in use for any presently suspended call(s).|

84

Call identity in use
This cause indicates that the network has received a call suspended request containing a call identity (including the null call identity) which is already in use for a suspended call within the domain of interfaces over which the call might be resumed.

85

No call suspended
This cause indicates that the network has received a call resume request containing a Call identity information element which presently does not indicate any suspended call within the domain of interfaces over which calls may be resumed.

86

Call having the requested call identity has been cleared
This cause indicates that the network has received a call resume request containing a Call identity information element indicating a suspended call that has in the meantime been cleared while suspended (either by network time-out or by the remote user).

87

User not a member of CUG
This cause indicates that the called user for the incoming CUG call is not a member of the specified CUG or that the calling user is an ordinary subscriber calling a CUG subscriber.

88

Incompatible destination
This cause indicates that the equipment sending this cause has received a request to establish a call which has low layer compatibility. high layer compatibility or other compatibility attributes (e.g., data rate) which cannot be accommodated.

90

Non-existent CUG
This cause indicates that the specified CUG does not exist.

91

Invalid transit network selection (national use)
This cause indicates that a transit network identification was received which is of an incorrect format as defined in Annex C/Q.931

95

Invalid message, unspecified
This cause is used to report an invalid message event only when no other cause in the invalid message class applies.

96

Mandatory information element is missing
This cause indicates that the equipment sending this cause has received a message which is missing an information element which must be present in the message before that message can be processed.

97

Message type non-existent or not implemented
This cause indicates that the equipment sending this cause has received a message with a message type it does not recognize either because this is a message not defined of defined but not implemented by the equipment sending this cause.

98

Message not compatible with call state or message type non-existent or not implemented.
This cause indicates that the equipment sending this cause has received a message such that the procedures do not indicate that this is a permissible message to receive while in the call state. or a STATUS message was received indicating an incompatible call state.

99

Information element / parameter non-existent or not implemented
This cause indicates that the equipment sending this cause has received a message which includes information element(s)/parameter(s) not recognized because the information element(s)/parameter name(s) are not defined or are defined but not implemented by the equipment sending the cause. This cause indicates that the information element(s)/parameter(s) were discarded. However, the information element is not required to be present in the message in order for the equipment sending the cause to process the message.

100

Invalid information element contents
This cause indicates that the equipment sending this cause has received and information element which it has implemented; however, one or more Gelds in the I.E. are coded in such a way which has not been implemented by the equipment sending this cause.

101

Message not compatible with call state
This cause indicates that a message has been received which is incompatible with the call state.

102

Recovery on timer expiry
This cause indicates that a procedure has been initiated by the expiration of a timer in association with error handling procedures.

103

Parameter non-existent or not implemented passed on (national use)
This cause indicates that the equipment sending this cause has received a message which includes parameters not recognized because the parameters are not defined or are defined but not implemented by the equipment sending this cause. The cause indicates that the parameter(s) were ignored. In addition, if the equipment sending this cause is an intermediate point, then this cause indicates that the parameter(s) were passed unchanged.

110

Message with unrecognized parameter discarded
This cause indicates that the equipment sending this cause has discarded a received message which includes a parameter that is not recognized.

111

Protocol error, unspecified
This cause is used to report a protocol error event only when no other cause in the protocol error class applies.

127

Intel-working, unspecified
This cause indicates that an interworking call (usually a call to 5W56 service) has ended.