This provides definitions to the Clear causes in Q931 messages.
Normal class
Cause #1 “unallocated (unassigned) number”
This cause indicates that the destination requested by the calling user cannot be reached
because, although the number is in a valid format, it is not currently assigned (allocated).
Cause #2 “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 recognise. The equipment
sending this cause does not recognise the transit network either because the transit network does not exist or because that particular transit network, while it does exist, does not service the equipment which is sending this cause.
This cause is supported on a network-dependent basis.
Cause #3 “no route to destination”
This cause indicates that the called user 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.
Cause #6 “channel unacceptable”
This cause indicates the channel most recently identified is not acceptable to the sending
entity for use in this call.
Cause #7 “call awarded and being delivered in an established channeP’
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).
Cause #16 “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.
Cause #17 “user busy”
This cause is used when the called user has indicated the inability to accept another call.
It is noted that the user equipment is compatible with the call.
Cause #18 “no user responding”
This cause is used when a user does not respond to a call establishment message with
either an alerting or connect indication within the prescribed period of time allocated
(defined in ETS 300 102-1 by the expiry of either timer T3 03 or T3 10).
Cause #19 “no answer from user (user alerted)”
This cause is used when a user has provided an alerting indication but has not provided a
connect indication within a prescribed period of time.
NOTE:This cause is not necessarily generated by ETS 300 102-1 procedures but may be
generated by internal network timers.
Cause #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.
Cause #22 “number changed”
This cause is returned to a calling user when the called party number indicated by the
calling user is no longer assigned. The new called party number may optionally be included in the diagnostic field. If a network does not support this capability, cause #1 “unallocated (unassigned) number” shall be used.
Cause #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 signalling message was unable to be delivered to the remote user; e.g. a physical layer or data link layer failure at the remote user, user equipment off-line, etc.
Cause #29 “facility rejected”
This cause is returned when a facility requested by the user cannot be provided by
the network.
Cause #30 “response to status enquiry”
This cause is included in the STATUS message when the reason for generating the
STATUS message was the prior receipt of a STATUS ENQUIRY message.
Cause #31 “normal, unspecified”
This cause is used to report a normal event only when no other cause in the normal class
applies.
Resource unavailable class
Cause #34 “no circuit/channel available”
This cause indicates that there is no appropriate circuit/channel presently available to handle
the call.
Cause #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.
Cause #41 “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.
Cause #42 “switching equipment congestion”
This cause indicates that the switching equipment generating this cause is experiencing a
period of high traffic.
Cause #43 “access information discarded”
This cause indicates that the network could not deliver access information to the remote
user as requested; i.e. a user-to-user information, low layer compatibility, high layer
compatibility, or subaddress as indicated in the diagnostic.
It is noted that the particular type of access information discarded is optionally included in
the diagnostic.
Cause #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.
Cause #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.
Service or option not available class
Cause #49 “quality of service not available”
This cause is used to report that the requested quality of service, as defined in CCITT
Recommendation X.213, cannot be provided, (e.g. throughput or transit delay cannot be
supported).
Cause #50 “requested facility not subscribed”
This cause indicates that the requested supplementary service could not be provided by the network because the user has not completed the necessary administrative arrangements with its supporting network.
Cause #57 “bearer capability not authorised”
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 authorised to use.
Cause #58 “bearer capability not presently available”
This cause indicates that he user has requested a bearer capability which is implemented by the equipment which generated this cause but which is not available at this time.
Cause #63 “service or option not available “unspeciried”
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. Service or option not implemented class
Cause #65 “bearer capability not implemented”
This cause indicates that the equipment sending this cause does not support the bearer
capability requested.
Cause #66 “channel type not implemented”
This cause indicates that the equipment sending this cause does not support the channel
type requested.
Cause #69 “requested facility not implemented”
This cause indicates that the equipment sending this cause does not support the requested
supplementary service.
Cause #70 “only restricted digital information bearer capability is available”
This cause indicates that one equipment has requested an unrestricted bearer service but
that the equipment sending this cause only supports the restricted version of the requested
bearer capability.
Cause #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.
Invalid message (e.g. parameter out of range) class
Cause #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 usernetwork interface.
Cause #82 9dentified 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 1 to 12 and the user equipment
or the network attempts to use channels 13 through 23, this cause is generated.
Cause #83 “a suspended call exists, but this call identity does noV
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).
Cause #84 “call identity in use”
This cause indicates that the network has received a call suspend request. The call suspend
request contained 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.
Cause #85 “no call suspended”
This cause indicates that the network has received a call resume request. The call resume
request contained a Call identity information element which presently does not indicate any
suspended call within the domain of interfaces over which calls may be resumed.
Cause #86 “call having the requested call identity has been cleared”
This cause indicates that the network has received a call resume request. The call resume
request contained a Call identity information element which once indicated a suspended
call; however, that suspended call was cleared while suspended (either by network timeout
or by the remote user).
Cause #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.
Cause #90 “destination address missing or incomplete” This cause indicates that he
called user cannot be reached because the called party number is not in a valid format or is
not complete.
Cause #91 “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.
Cause #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.
Protocol error (e.g. unknown message) class
Cause #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.
Cause “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 recognise either because this is a message not defined or defined
but not implemented by the equipment sending this cause.
Cause #98 “message not compatible with call state or messages 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.
Cause #99 “information element non-existent or not implemented”
This cause indicates that the equipment sending this cause has received a message which
includes information elements not recognised because the information element identifier is not defined or it is defined but not implemented by the equipment sending the cause.
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.
Cause #100 “invalid information element contents”
This cause indicates that the equipment sending this cause has received an 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.
Cause #101 “message not compatible with call state”
This cause indicates that a message has been received which is incompatible with the call
state.
Cause #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.Interworking class
Cause #127 interworking, unspecified”
This cause indicates that there has been interworking with a network which does not provide causes for actions it takes; thus, the precise cause for a message which is being sent cannot be ascertained.
