Cause Codes

The following cause names, meanings, and values are mentioned in Q.850 as being related to ISUP.

Cause No. l - Unallocated (unassigned) number.

This cause implies that the calling user's specified destination is not reached because, despite having a proper format, the phone number is currently unassigned (allocated).

Cause No. 2 - No route to the specified transit network.

This cause implies that the equipment that is transmitting it has received a request to route the call through a transit network that it is unfamiliar with. The transit network is not recognized by the equipment sending this cause either because it does not exist or because it does not serve the equipment sending this cause, even though it does exist. On a network-dependent basis, this cause is backed.

Cause No. 3 - No route to a destination.

This means that the network the call was routed via does not support the intended destination, making it impossible to connect with the person being called. Support for this cause is network-dependent.

Cause No. 4 - send special information tone.

According to this cause, the called party cannot be contacted for indefinite reasons, and the calling party should be notified once more by a particular information tone.

Cause No. 5 - misdialed trunk prefix.

This implies that the trunk prefix of the caller party number was mistakenly added. The called number that the client premises equipment transmits to the network should be used to determine this number.

Cause No. 6 - channel unacceptable

This reason suggests that the sender entity does not approve the most recent channel to be used in this call.

Cause No. 7 - call awarded. being delivered in an established channel.

This causes the incoming call to be connected to a channel that has previously been set up for that user for comparable calls, meaning that the user has been granted the incoming call.

Cause No. 8 - preemption

This reason denotes the preemption of the call.

Cause No. 9 - preemption - circuit reserved for reuse

This reason denotes that the call is being preempted and that the preempting exchange has reserved the circuit for later use.

Cause No. 10 - normal call clearing

This cause suggests that the call is being terminated because one of the call's participants asked that it be terminated. In most cases, the network is not where this cause originates.

Cause No. 17 - user busy

The user's busy state has been experienced, and the called party is unable to take another call due to this cause. The calling user or the network may provide this cause value. When a user is judged to be busy, it is recorded that the user's equipment is suitable for the call.

Cause No. 18 - no user responding

This reason is given when a called party fails to react to a call establishing a message within the allotted amount of time with an alerting or connect indicator.

Cause No. 19 - no answer from user (user alerted)

When the contacted party is informed but fails to reply with a connect indicator within a set amount of time, this reason is applied. Note: Internal network timers may be responsible for this problem rather than Q.931 processes.

Cause No. 20 - subscriber absent

The usage of this cause value occurs when a mobile station logs off. If a personal telecommunications user is momentarily unaddressable at any user-network interface, radio contact with a mobile station cannot be made.

Cause No. 21 - call rejected

This cause suggests that the device transmitting it does not want to answer this call. The equipment transmitting this reason is not busy nor incompatible, therefore it could have answered the call. This reason might potentially be produced by the network, suggesting that the call was terminated as a result of an additional service limitation. The diagnostic section could also provide more details about the supplemental service and the rejection justification.

Cause No. 22 - number changed

When the calling party's designated called party number is no longer assigned, this reason is returned to the calling party. Optionally, the diagnostic field may contain the new called party number. In the event that a given network is unable to handle this cause value, cause number 1, an unallocated (unassigned) number, must be utilized.

Cause No. 26 - non-selected user clearing

The user has not been given the incoming call, according to this cause.

Cause No. 27 - destination out of order

This reason indicates that the user's specified destination cannot be accessed because the destination's interface is malfunctioning. When a signal message cannot be conveyed to a remote party due to a physical layer failure, a data connection failure or user equipment being offline, it is said that the system is "not working correctly."

Cause No. 28 - invalid number format (address incomplete)

This reason indicates that the called person cannot be reached because the number is incomplete or not in a valid format.

Cause No. 29 - facilities rejected

When the network is unable to offer an additional service that the user has requested, this reason is returned.

Cause No. 30 - response to STATUS INQUIRY

When the receipt of a STATUS INQUIRY served as the catalyst for the STATUS message's generation, this cause is mentioned in the STATUS message.

Cause No. 31 - normal. unspecified

When no other cause in the normal class applies, this cause is the only one that may be used to report a normal occurrence.

Cause No. 34 - no circuit/channel available

This reason means that the call cannot be handled right now because no suitable circuit or channel is open.

Cause No. 35 - Call Queued

Cause No. 38 - network out of order

This cause suggests that the network isn't working properly and that the issue is likely to persist for a while—for example, immediately retrying the call is unlikely to be successful.

Cause No. 39 - permanent frame mode connection out-of-service

When given as a reason in a STATUS message, a frame mode connection that has been created permanently is considered to be out of service (e.g. due to equipment or section failure)

Cause No. 40 - permanent frame mode connection operational

This reason is included in a STATUS message to show that a connection in frame mode that has been established permanently is active and able to transfer user data.

Cause No. 41 - temporary failure

This problem suggests that the network isn't working well and that it won't persist for very long; as a result, the user may want to try making another call attempt right away.

Cause No. 42 - switching equipment congestion

This cause suggests that there is a time of heavy traffic on the switching equipment that is producing this cause.

Cause No. 43 - access information discarded

This reason denotes that the connection was unable to send the desired user-to-user communication, low layer compatibility, high layer compatibility, or sub-address to the remote user, as shown in the diagnosis. It should be noted that the diagnosis may include a specific type of rejected access information.

Cause No. 44 - requested circuit/channel not available

This reason is returned when the asking entity cannot receive the circuit or channel requested by the opposite side of the interface.

Cause No. 46 - precedence call blocked

This causes either the called user to be occupied with a call of equal or higher preemptable level or it signals that there are no preemptable circuits.

Cause No. 47 - resource unavailable, unspecified

When none of the other causes in the resource unavailable class apply, this cause is the only one that may be used to report a resource unavailable event.

Cause No. 49 - Quality of Service not available

According to Recommendation X.213, this reason is used to indicate that the Quality of Service requested cannot be provided (e.g., the throughput of transit delay cannot be supported).

Cause No. 50 - requested facility not subscribed

This cause denotes a request for a supplemental service that the equipment causing this cause is capable of providing, but that the user is not permitted to use.

Cause No. 52 - outgoing calls barred

Cause No. 53 - outgoing calls barred within CUG ( Closed User Group )

Although the calling party for the outgoing CUG call is a member of the CUG, this reason implies otherwise. This CUG member is not permitted to make outgoing calls.

Cause No. 54 - incoming calls barred

Cause No. 55 - incoming calls barred within CUG

Even if the caller is a CUG member, this reason implies that the call is originating from a non-CUG member. For this member of the CUG, incoming calls are not permitted.

Cause No. 57 - bearer capability not authorized

This cause denotes a request for a bearer capability that the equipment causing this cause implements, but that the user is not permitted to use.

Cause No. 58 - bearer capability not presently available

This cause indicates that the user has requested a bearer capability that the equipment that caused this cause implements but that is not now accessible.

Cause No. 62 - inconsistency in the outgoing information element.

This issue points to a discrepancy between the subscriber class and the designated outgoing access information.

Cause No. 63 - service or option not available. unspecified

Only when no other causes in the class of services or options not available apply, is this reason utilized to report a service or option not available event.

Cause No. 65 - bearer capability not implemented

This cause indicates that the device sending this cause is unable to provide the specified bearer capability.

Cause No. 66 - channel type not implemented

This cause indicates that the apparatus delivering this cause is incapable of supporting the required channel type.

Cause No. 69 - requested facility not implemented

This cause indicates that the device sending this cause is unable to provide the additional services you have requested.

Cause No. 70 - only restricted digital information bearer capability is available

This cause shows that even though the calling party asked for an unrestricted bearer service, the equipment delivering this cause can only accommodate the limited bearer capability.

Cause No. 79 - service or option not implemented unspecified

Only when there are no other causes in the class of services or options that have not been implemented is this cause used to report an event.

Cause No. 81 - invalid call reference value

This cause denotes that a message with a call reference that isn't presently in use on the user-network interface has been received by the equipment delivering this cause.

Cause No. 82 - identified channel does not exist

This cause indicates that a request to make a call on a channel that isn't currently active on the interface has been received by the equipment delivering this cause. For instance, this cause is created if a user subscribes to channels 3 through 23 on a principal rate interface with a number from 1 to 12 and the user equipment or network tries to utilize those channels.

Cause No. 83 - a suspended call exists, but this call identify does not

This error message indicates that a call resume attempt was made using a call identification that is different from any call that is currently suspended (s).

Cause No. 84 - call identity in use

This means that the system has received a call-suspension request with a call identity (along with a null call identity) that is still in use for a call that has been suspended within the range of interfaces where the call might be resumed.

Cause No. 85 - no call suspended

This reason tells us the network has received a call resume request with a call identification information element that currently doesn't show any suspended calls inside the range of interfaces where calls may be resumed.

Cause No. 86 - call having the requested call identity has been cleared

This reason indicates that the network has received a request to resume a call that includes a call identity information element that identifies a call that has been suspended and has since been cleared (either by network time-out or by the remote user).

Cause No. 87 - user not a member of CUG

This reason for receiving a CUG call suggests that either the called user is not a subscriber to the specified CUG or that the called user is a regular subscriber phoning a CUG subscriber.

Cause No. 88 - incompatible destination

This reason tells the device sending it that it has been asked to initiate a call that is compatible at the low layer. high layer compatibility or other qualities of compatibility (like data rate) that cannot be met.

Cause No. 90 - non-existent CUG

This reason suggests that the required CUG is not present.

Cause No. 91 - invalid transit network selection

This causes a transit network identity to be obtained that is in the wrong format, as specified in Annex C/Q.931

Cause No. 95 - invalid message, unspecified

When none of the other causes in the invalid message class apply, this cause is used to report an invalid message event.

Cause No. 96 - mandatory information element is missing

This cause indicates that a message was received by the equipment sending this cause but was lacking a piece of information that was necessary for the message to be processed.

Cause No. 97 - message type non-existent or not implemented

Because this message is either not defined by the device sending this cause or defined but not implemented by it, this reason shows that the device delivering this reason has received a text with a message type it does not recognize.

Cause No. 98 - message not compatible with call state or message type non-existent or not implemented.

This cause indicates that the device issuing this cause has received a message that is not indicated as being acceptable to receive while in the call state by the procedures. or a STATUS message indicating an incompatible call condition was received.

Cause No. 99 - Information element/parameter non-existent or not implemented

This cause indicates that the equipment issuing the cause has received a message containing information element(s) or parameter(s) that it is unable to recognize because the information element(s) or parameter(s) name(s) are either not defined or defined but not implemented by the equipment issuing the cause. The information element(s) or parameter(s) were likely eliminated, according to this cause. The information component is not necessary for the message to be processed by the equipment that is transmitting it, though.

Cause No. 100 - Invalid information element contents

This cause indicates that although the equipment delivering this cause has implemented the information element is received, it has not yet implemented one or more of the information element's fields because they are coded differently.

Cause No. 101 - message not compatible with call state

This cause denotes the receipt of a message that is inconsistent with the call status.

Cause No. 102 - recovery on timer expiry

This reason denotes the beginning of a procedure due to the timer associated with error handling procedures expiring.

Cause No. 103 - parameter non-existent or not implemented - passed on

This cause denotes that the equipment delivering this cause has received a message with parameters that it is unable to recognize because it has either not defined them or has defined them but not yet implemented them. The reason suggests that the parameter(s) was/were disregarded. Additionally, this reason denotes that the parameter(s) were transmitted unmodified if the apparatus transmitting it is an intermediary point.

Cause No. 110 - message with unrecognized parameter discarded

This cause denotes that the device issuing this cause has discarded a message it received that had an unknown parameter.

Cause No. 111 - protocol error, unspecified

Only when none of the other causes in the protocol error class apply is this reason utilized to report a protocol error event.

Cause No. 127 - Intel-working, unspecified

This reason denotes the termination of an interworking call, which is often a call to the 5W56 service.