All Cause and Location codes (Q.850)

Full list of Q.850 cause and location codes in telecommunications signaling, applied in both Signalling System No. 7 (SS7) and Digital Subscriber Signalling System No. 1 (DSS1)

Cause Code	Reason
0	Valid cause code not yet received. This cause code is generated when no valid signaling information is available yet to determine the outcome of the call. It typically occurs during the initial setup stages, where various network nodes are exchanging information to establish or reject the call. This is often seen in cases involving long signaling paths or complex routing scenarios.
1	Unallocated (unassigned) number. This cause code indicates that the requested telephone number, while valid in format, is not currently allocated to a subscriber or service. It often arises in situations where the number has been decommissioned, reserved for future use, or dialed incorrectly. For example, in an international call, this may occur if the originating network cannot resolve the number within the intended destination’s numbering plan.
2	No route to specified transit network (WAN). The requested transit network cannot be reached because it is either not recognized or not accessible from the originating network. This issue may occur due to incorrect configurations, network limitations, or non-existent routes in the signaling infrastructure. It typically involves intermediate nodes identifying the problem and halting the call setup.
3	No route to destination. This cause code reflects a failure to locate a routing path to the final destination. The dialed number may be valid, but the destination network does not support or recognize the requested endpoint. This commonly occurs in cases where cross-border routing agreements or configurations are missing.
4	Send special information tone. The network has determined that the called party cannot be reached, and it signals the originating user by playing a special information tone. This tone serves as an auditory indication of a persistent issue, such as a blocked number or an unavailable destination.
5	Misdialed trunk prefix. This cause is generated when an invalid trunk prefix (such as an international or long-distance code) is included in the dialed number. For example, if a user includes a country code unnecessarily for a local call, the call cannot be routed, and this error is returned.
6	Channel unacceptable. The identified channel is not suitable for use in the call due to poor quality, signaling incompatibility, or other resource-related constraints. This issue may result from hardware limitations or network congestion affecting channel availability.
7	Call awarded and being delivered in an established channel. The network has successfully allocated a channel for the call and is routing the communication over an already-established path. This often occurs in packet-switched networks or when calls are resumed after being placed on hold.
8	Prefix 0 dialed but not allowed. The dialing plan in the originating network prohibits the use of prefix ‘0’ for this type of call. This restriction is often applied to prevent routing errors or misuse of numbering resources.
9	Prefix 1 dialed but not allowed. Similar to prefix ‘0’, this cause code indicates that prefix ‘1’ is not permitted for the type of call being attempted under the current dialing plan or network policies.
10	Prefix 1 dialed but not required. This cause code is generated when the use of prefix ‘1’ is unnecessary and may interfere with the call’s successful routing. The network may still proceed with routing if the additional prefix does not cause conflicts.
11	More digits received than allowed, call is proceeding. This indicates that the user has entered more digits than the network expects for the call type, but the network can still process the request successfully.
16	Normal call clearing. The call was terminated as expected, either by the user or the network, without encountering any errors or abnormal conditions. This is the standard end-state for most calls.
17	User busy. The called party is currently engaged in another communication and cannot accept new calls. This status may be detected by the network based on the user equipment’s signaling or the called party’s response.
18	No user responding. This cause code indicates that the called party did not respond to call signaling within the prescribed time. It may occur due to user unavailability, device malfunction, or failure of the alerting messages to reach the user.
19	No answer from user. The called party was successfully alerted but did not respond to the call within the allocated timeframe. This may indicate deliberate rejection of the call or unavailability to answer despite being reachable.
20	Subscriber absent. The called party’s device is powered off, out of coverage, or otherwise unreachable. This is common in mobile networks where users may disconnect intentionally or unintentionally.
21	Call rejected. The called party or network has explicitly rejected the call. Reasons may include blocked numbers, restricted access due to supplementary service constraints, or user-defined rejection settings.
22	Number changed. The dialed number is no longer valid because the subscriber has moved to a different number. The network may optionally provide the new number in the response, if supported. This commonly occurs in scenarios involving number portability or network reassignments.
23	Reverse charging rejected. The request to reverse the charging direction of the call, making the recipient responsible for the call costs, has been denied. This often depends on the recipient’s service agreement or network policies.
24	Call suspended. The active call session has been temporarily suspended by one of the users or the network. The call can be resumed later without requiring a new setup.
25	Call resumed. A previously suspended call has been successfully resumed, allowing communication to continue without initiating a new connection.
26	Non-selected user clearing. This occurs when a call is terminated because the intended recipient within a multi-user setup, such as a shared number or hunt group, is unavailable or did not respond.
27	Destination out of order. The called party’s equipment or network interface is malfunctioning, rendering the destination unreachable. This error typically points to physical or data link layer issues.
28	Invalid number format (incomplete number). The number dialed by the user is incorrectly formatted or incomplete, making it impossible for the network to route the call.
29	Facility rejected. The requested supplementary service or facility cannot be provided by the network. This may result from user restrictions, network limitations, or unsupported configurations.
30	Response to STATUS ENQUIRY. This is a response generated by the network to provide details about the current status of the call or session, typically in response to a STATUS ENQUIRY message.
31	Normal, unspecified. The call ended normally, but the network did not provide a specific reason for the termination. This is often used when the session concludes without any identifiable errors or exceptional events.
33	Circuit out of order. Indicates that the circuit used for the call is experiencing issues such as physical disconnection, signaling failures, or hardware malfunctions. This is a common issue in legacy systems where specific circuits are required for communication.
34	No circuit/channel available. The network does not have any suitable circuits or channels available to process the call request. This typically occurs during periods of high traffic or when resources are reserved for priority services.
35	Destination unattainable. The requested destination cannot be reached due to network constraints, routing limitations, or configuration errors. This issue often arises in cases where the destination node has been decommissioned or reconfigured.
37	Degraded service. The quality of service for the call has fallen below acceptable thresholds. This could be due to network congestion, insufficient bandwidth, or issues with the underlying infrastructure.
38	Network (WAN) out of order. The wide area network (WAN) is experiencing a severe failure, preventing the call from being routed. This issue often requires significant intervention to restore connectivity.
39	Transit delay range cannot be achieved. The network is unable to meet the required transit delay range for the call, which could result in unacceptable latency for real-time communication.
40	Throughput range cannot be achieved. The requested throughput for data transmission cannot be provided by the network at the current time. This issue is common in bandwidth-limited scenarios.
41	Temporary failure. A temporary issue in the network, such as equipment malfunction or short-term congestion, is preventing the call from proceeding. Retrying the call at a later time is typically recommended.
42	Switching equipment congestion. The switching equipment responsible for routing the call is experiencing high traffic levels and cannot handle additional requests at this time.
43	Access information discarded. The network discarded the access information provided by the user or another node due to incompatibility or errors in the data. This can include user-to-user information or compatibility settings.
44	Requested circuit channel not available. The specific circuit or channel requested for the call is currently unavailable. This often occurs in fixed-line systems where resources are allocated on a per-call basis.
45	Pre-empted. The call was terminated to allocate resources to a higher-priority communication, such as an emergency service call.
46	Precedence call blocked. The precedence call could not be completed because there were no resources available at the required priority level. This is often seen in systems with hierarchical call handling.
47	Resource unavailable – unspecified. A required resource for the call, such as a channel or routing capability, is unavailable, but no specific details are provided by the network.
49	Quality of service unavailable. The requested quality of service parameters cannot be supported by the network at this time. This could affect data-intensive applications such as video conferencing.
127	Internetworking, unspecified. The call was terminated due to incompatibility or configuration issues when communicating between different network technologies or domains. This is often used in inter-operator scenarios.
50	Requested facility not subscribed. The requested supplementary service or facility is not part of the user’s subscription plan. Examples include advanced call forwarding or conferencing features.
51	Reverse charging not allowed. The network does not permit reverse charging for this call, where the receiving party would cover the call costs. This restriction may depend on billing agreements or policies.
52	Outgoing calls barred. The user is restricted from making outgoing calls due to account restrictions, service limitations, or parental controls.
53	Outgoing calls barred within CUG. Outgoing calls within the Closed User Group (CUG) are not allowed for the originating user. This restriction is often configured for specific organizational or billing purposes.
54	Incoming calls barred. The user is not permitted to receive incoming calls, possibly due to account restrictions, network policies, or service settings.
55	Incoming calls barred within CUG. The user cannot receive incoming calls from members of the Closed User Group (CUG). This is often set to limit specific interactions within the group.
56	Call waiting not subscribed. The call waiting feature is not enabled for the user’s subscription, preventing them from receiving notifications about incoming calls while on an active call.
57	Bearer capability not authorized. The requested bearer capability, such as specific data rates or encryption levels, is not authorized for the user’s account.
58	Bearer capability not presently available. The network supports the requested bearer capability, but it is not available at the moment due to resource constraints or temporary limitations.
63	Service or option not available, unspecified. The requested service or feature is not available in the network or user’s subscription plan, but no further details are provided.
65	Bearer service not implemented. The requested bearer service is not supported by the network or equipment. This can occur in older systems where certain advanced capabilities, such as high-speed data, are unavailable.
66	Channel type not implemented. The network does not support the type of channel requested for the call. This often occurs in scenarios where the requested channel is incompatible with the network’s hardware or configuration.
67	Transit network selection not implemented. The feature for selecting a transit network is not implemented by the originating or transit network. This can result from outdated configurations or unsupported signaling options.
68	Message not implemented. The network or receiving equipment does not recognize or support the specific signaling message. This issue typically arises when newer signaling features are used in legacy systems.
69	Requested facility not implemented. The requested supplementary service or facility is not supported by the network or equipment. Examples include advanced conferencing features or specialized routing options.
70	Only restricted digital information bearer capability is available. The network supports only a restricted version of the requested bearer service, which may impact the quality or type of communication.
79	Service or option not implemented, unspecified. The requested service or option is not supported by the network, and no further details are provided.
81	Invalid call reference value. The call reference value provided in the signaling message is not recognized or currently in use on the network. This may occur due to signaling errors or out-of-sequence messages.
82	Identified channel does not exist. The specific channel identified in the signaling message is not active or available on the interface. This is common in systems with dynamic channel allocation.
83	A suspended call exists, but this call identity does not. The provided call identity does not match any currently suspended calls within the network. This can result from signaling mismatches or user errors.
84	Call identity in use. The call identity provided is already associated with another active or suspended call, preventing its reuse for a new session.
85	No call suspended. Indicates that there are no suspended calls available to resume. This often results from an incorrect request to resume a call.
86	Call having the requested call identity has been cleared. The call associated with the provided identity has already been terminated, either by the user or network.
87	Called user not member of CUG. The called user is not a member of the specified Closed User Group (CUG), preventing the call from being completed. This is a feature used to restrict communication to specific groups.
88	Incompatible destination. The requested call cannot be completed due to compatibility issues between the originating and destination networks or equipment.
89	Non-existent abbreviated address entry. The abbreviated dialing entry used by the caller does not exist in the network directory, leading to call failure.
90	Destination address missing, and direct call not subscribed. The destination address is incomplete or missing, and the user is not subscribed to direct calling services. This is common in services that rely on pre-programmed dialing.
91	Invalid transit network selection (national use). The transit network identifier provided in the signaling message is not valid according to national numbering or routing rules.
92	Invalid facility parameter. The parameters provided for the requested facility are invalid, preventing the network from processing the request.
93	Mandatory information element is missing. A critical information element required for processing the signaling message is absent, causing the request to fail.
95	Invalid message, unspecified. The message received by the network is invalid, but no further diagnostic information is available.
96	Mandatory information element is missing. A required information element is missing from the signaling message, rendering it unprocessable by the network.
97	Message type non-existent or not implemented. The message type received is either not defined in the signaling protocol or not supported by the receiving network.
98	Message not compatible with call state or message type non-existent or not implemented. The message is not valid for the current call state or is unrecognized by the receiving equipment.
99	Information element nonexistent or not implemented. The information element in the message is either not recognized or not supported by the receiving equipment.
100	Invalid information element contents. The contents of an information element are invalid or improperly formatted, preventing the network from processing it.
101	Message not compatible with call state. The message conflicts with the current state of the call and cannot be processed.
102	Recovery on timer expiry. The network has initiated recovery procedures due to the expiration of a timer, typically in response to a signaling or protocol failure.
103	Parameter non-existent or not implemented – passed on. The parameter is unrecognized or unsupported but has been forwarded unchanged to another network node.
111	Protocol error unspecified. A generic protocol error occurred, and no additional diagnostic information is available.
127	Intel-working, unspecified. This cause code indicates that a call has been terminated due to issues related to interoperability between two or more networks involved in the signaling or routing process. Internetworking refers to the handling and transfer of calls between networks that may utilize different technologies, protocols, or standards.