Cause codes provide granular information about a call status to help you understand what happened with a call. These cause codes are primarily derived by Exotel as per the operators. These are currently exposed via our Passthru applet.

Cause codes ranging from 1-127 are as per the ISDN standard.

Cause

CauseCode

Text

Description

1

UNALLOCATED_NUMBER

Unallocated (unassigned) number

This cause indicates that the destination requested by the calling user cannot be reached because, though the number is in a valid format, it is not currently assigned (allocated).

2

NO_ROUTE_TO_NETWORK

No route to specified transit network

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. This could be because the transit network does not exist or because that particular transit network not serve the equipment which is sending this cause.

3

NO_ROUTE_TO_DESTINATION

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

SPECIAL_INFORMATION_TONE

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

MISDIALED_TRUNK_PREFIX

misdialed trunk prefix

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

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_ESTABLISHED_CHANNEL

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

preemption

This cause indicates the call is being preempted.

9

PREEMPTION_REUSE

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.

16

NORMAL_CLEARNING

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. This could mean

  • Telephone line problems.

  • Hung session on remote end.


17

USER_BUSY

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

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

no answer from user

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

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

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

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

26

NON_SELECTED_USER_CLEARNING

non-selected user clearing

This cause indicates that the user has not been awarded the incoming call.

27

DESTINATION_OUT_OF_ORDER

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

invalid number format

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

 facilities rejected

This cause is returned when a supplementary service requested by the user cannot be provided by the network

30

STATUS_INQUIRY_RESPONSE

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

normal. unspecified

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

34

NO_CHANNEL_AVAILABLE

no circuit/channel available

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

35

CALL_QUEUED

Call Queued


38

NETWORK_OUT_OF_ORDER

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

CONNECTION_OUT_OF_SERVICE

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)

40

CONNECTION_OPERATIONAL

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

temporary failure

This cause indicates that the network is not functioning correctly and that the condition is not 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

switching equipment congestion

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

43

ACCESS_INFO_DISCARDED

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

CHANNEL_NOT_AVAILABLE

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

precedence call blocked

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

47

RESOURCE_UNAVAILABLE

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

QOS_NOT_AVAILABLE

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

FACILITY_NOT_SUBSCRIBED

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


The switch looks at the number being dialed and thinks it is for another service rather than ISDN. If the phone number is put in the correct format, the call should be placed properly. There are no standards for this, all Telcos have their own system for programming the number formats that the switches will recognize. Some systems want to see 7 digits, some 10, and others 11.

52

OUTGOING_CALLS_BARRED

outgoing calls barred


53

OUTGOING_CALLS_BARRED_CUG

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

54

INCOMING_CALLS_BARRRED

incoming calls barred


55

INCOMING_CALLS_BARRRED_CUG

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

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_AVAILABLE

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

INCONSISTENT_OUTGOING_INFO_ELEMENT

inconsistency in outgoing information element

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

63

SERVICE_NOT_AVAILABLE

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

bearer capability not implemented

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

What it means:

  1. In most cases, the number being called is not an ISDN number but an analog destination.

  2. The equipment is dialing at a faster rate than the circuitry allows, for example, dialing at 64K when only 56K is supported


66

CHANNEL_TYPE_NOT_IMPLEMENTED

channel type not implemented

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

69

FACILITY_NOT_IMPLEMENTED

requested facility not implemented

This cause indicates that the equipment sending this cause does not support the requested supplementary services

70

RESTRICTED_BEARER_CAPABILITY_AVAILABLE

only restricted digital information bearer capability is available

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_NOT_IMPLEMENTED

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

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

CHANNEL_DOES_NOT_EXIST

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 3 through 23, this cause is generated.

83

SUSPENDED_CALL_EXISTS

 A suspended call exists, but this call identify 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_INUSE

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

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_IDENTITY_CLEARED

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_MEMBER_OF_CUG

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

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

non-existent CUG

This cause indicates that the specified CUG does not exist.

91

INVALID_TRANSIT_NETWORK_SELECTION

invalid transit network selection

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_MESSAGED

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_INFO_ELEMENT_MISSING

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

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

message not compatible with call state or message type non-existent

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

INFO_ELEMENT_NON_EXISTENT

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_INFO_ELEMENT_CONTENTS

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 of the fields in the information element are coded in such a way which has not been implemented by the equipment sending this cause

101

MESSAGE_NOT_COMPABITLE_CALL_STATE

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

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

parameter non-existent or not implemented - passed on

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

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

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

Intel-working, unspecified

This cause indicates that an interworking call (usually a call to 5W56 service) has ended



Notes about Cause Codes over 128: According to the ISDN spec “Cause code values of 128 and higher aren't sent over the network. A terminal displaying a value 128 or higher and claiming it is a cause code arguably has a bug or is implementing some proprietary diagnostic code (not necessarily bad). Some commendation has cause codes listed with numbers higher than 128, but at this time they are proprietary in nature.”


Cause codes ranging beyond 1000 are constructed by Exotel based on certain scenarios:


Cause

CauseCode

Text

Description

1001 (maps to ISDN code 16)

NORMAL_CLEARNING

Normal Clearing

The call is being cleared by Exotel because one of the users involved in the call has requested that the call be cleared (hangup) or we have nothing to execute for the call.

1002 (maps to ISDN code 21)

CALL_REJECTED

Call Rejected

The call is being rejected by Exotel. This is usually sent when the call was not answered and an explicit hangup was specified in the flow

1003 (maps to AHN code 130)

RING_TIMEOUT

Ring Timeout

The call is being cleared by Exotel while ringing because of explicit timeout specified for the leg

1004 (maps to AHN code 131 )

CONNECT_TIMEOUT

Connect Timeout 

The call is being cleared by Exotel while connecting because of explicit timeout specified for the leg

1005

CALL_THROTTLED

Call Throttled

If a call is throttled by Exotel as number of call requests per minute exceeded the allowed value for your account.

1006

CALL_REJECTED_DND

Incoming promotional calls barred due to DND preference of the user

This cause indicates that the incoming calls to the number is blocked due to the DND preference of the user. This cause code is not yet populated in case of Passthru applet.