Q850 telephony response codes

Code	Eng	Description
0	Valid cause code not yet received.	During call setup, the node has not yet received enough information to determine the cause of disconnection.
1	Unallocated (unassigned) number.	The requested number is valid in format but not assigned to any subscriber.
2	No route to specified transit network (WAN).	Call forwarding was initiated, but the required translation route is unavailable or non-existent.
3	No route to destination.	The dialed number is not served by the network.
4	Send special information tone.	The number is permanently unavailable, a special information tone is sent.
5	Misdialed trunk prefix.	Incorrect trunk prefix was used when dialing the number.
6	Channel unacceptable.	The selected communication channel is not suitable for data transfer or call setup.
7	Call awarded and being delivered in an established channel.	The call is being delivered through an already established channel.
8	Prefix 0 dialed but not allowed.	The 0 prefix is dialed, but such calls are prohibited for this line or user.
9	Prefix 1 dialed but not allowed.	The call starts with prefix 1, which is reserved for special services but is not allowed from this network or user.
10	Prefix 1 dialed but not required.	The user added prefix 1 manually, although the system handles it automatically or doesn’t use it at all.
11	More digits received than allowed, call is proceeding.	More digits than allowed were received, but the call continues, possibly with the extra digits trimmed.
16	Normal call clearing.	The call ended successfully — one of the parties hung up.
17	User busy.	The called party is currently on another call or engaged.
18	No user responding.	The called party did not pick up.
19	No answer from the user.	The user was alerted but did not answer the call.
20	Subscriber absent.	The subscriber is out of coverage or temporarily unreachable.
21	Call rejected.	The call was intentionally rejected — not due to a technical error.
22	Number changed.	The subscriber has changed their number — the dialed number is no longer in service.
23	Reverse charging rejected.	The recipient refused to accept call charges — no connection established.
24	Call suspended.	The connection is active but temporarily suspended — e.g., on hold or being transferred.
25	Call resumed.	A suspended call was successfully resumed.
26	Non-selected user clearing.	The call was rejected by a user it was not intended for.
27	Destination out of order.	The destination device or route is malfunctioning. This may occur if: - the subscriber's equipment is unavailable; - the network path is broken; - the communication channel is disrupted.
28	Invalid number format.	The dialed number has an invalid format.
29	Facility rejected.	The requested supplementary service cannot be provided by the network.
30	Response to STATUS ENQUIRY.	A STATUS message in response to an equipment state query.
31	Normal, unspecified.	The call ended normally, but no specific cause was provided.
54	Incoming calls barred.	The network blocked the call because incoming calls are not allowed for the recipient — due to user settings, provider policy, or access restrictions.
55	Incoming calls barred within Closed User Group (CUG).	Incoming calls are blocked for this number within the closed group settings.
56	Call waiting not subscribed.	The user has not enabled the call waiting service — a second call cannot be accepted during an active one.
57	Bearer capability not authorized.	The user requested data transfer, but authorization is missing.
58	Bearer capability not presently available.	The requested data transfer is currently not available.
62	Inconsistency in designated outgoing access information and subscriber class.	The subscriber’s class does not match the access requirements.
63	Service or option not available, unspecified.	The network rejected the request without providing a reason.
65	Bearer service not implemented.	The requested connection type (e.g., voice or fax) is not supported by the network.
66	Channel type not implemented.	The equipment does not support the requested channel type.
67	Transit network selection not implemented.	The network does not support calls specifying a transit carrier.
68	Message not implemented.	The message type is valid but not supported by the network.
69	The requested facility is not implemented.	The network or equipment does not support the requested feature.
70	Only restricted digital information bearer capability is available (national use).	Unlimited digital transmission was requested, but equipment limitations exist.
79	Service or option not implemented, unspecified.	The requested feature (e.g., forwarding, hold, video) is not supported, but the reason is unspecified.
81	Invalid call reference value.	The network cannot recognize the call identifier.
82	The identified channel does not exist.	The specified channel is not recognized or does not exist.
83	A suspended call exists, but this call identity does not.	No suspended call with the specified identifier was found.
84	Call identity in use.	A call with the same identifier is already active.
85	No call suspended.	There is no suspended call to resume.
86	Call having the requested call identity has been cleared.	The call with the given identifier has already ended.
87	Called user not member of CUG.	The call was rejected because the number is not part of the closed user group.
88	Incompatible destination.	The destination does not support the requested call type.
89	Non-existent abbreviated address entry.	The short number or alias does not exist in the address book or routing system.
90	Destination address missing, and direct call not subscribed.	The destination number is not provided, and direct calling is not enabled.
91	Invalid transit network selection (national use).	The provided transit network identifier is incorrectly formatted.
92	Invalid facility parameter.	The facility-related parameter (e.g., for forwarding or holding) is invalid.
93	Mandatory information element is missing.	One or more required parameters are missing from the message.
95	Invalid message, unspecified.	The message could not be processed due to an unspecified error.
96	Mandatory information element is missing.	A required element is missing, preventing the call from proceeding.
97	Message type non-existent or not implemented.	The message type is unrecognized or unsupported.
98	Message not compatible with call state or message type nonexistent or not implemented.	The command is invalid in the current call state or not supported at all.
99	An information element or parameter does not exist or is not implemented.	An unknown parameter was received and cannot be processed.
100	Invalid information element contents.	A required parameter is present but its value is invalid or improperly formatted.
101	Message in the invalid call state.	The command is invalid in the current call state — e.g., trying to end a non-existent call.
102	Recovery on timer expiry.	The network did not receive a response in time and terminated the connection.
103	Parameter non-existent or not implemented – passed on.	An unknown parameter was ignored and the call processing continued.
111	Protocol error unspecified.	A protocol-level error occurred (e.g., SIP or ISDN), but the cause is unspecified.
127	Internetworking, unspecified.	The call failed due to an error during interaction between different networks or technologies.