ISDN hangup cause codes provide information
as to why a call has been terminated. The list of hangup cause codes
below provides detailed information as to the underlying cause behind a call
hangup:
Code No. 0
This is usually given by the
router when none of the other codes apply. This cause usually occurs in the
same type of situations as cause 1, cause 88, and cause 100.
Code No. l - 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).
What it usually means:
1.
The SPIDS may be incorrectly entered in the router or the Telco
switch, giving a SPID failure in the router logs.
2.
The ISDN phone number being dialed by the router is invalid and
the telco switch cannot locate the number to complete the call, as it is
invalid.
3.
On long distance calls, the call cannot be properly routed to
its destination.
Code No. 2 - No route to
specified transit network (national use).
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. The equipment
sending this cause does not recognize the transit network either because the
transit network does not exist or because that particular transit network not
serve the equipment which is sending this cause.
Code No. 3 - 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.
Code No. 4 - 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.
Code No. 5 - misdialed trunk
prefix (national use).
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.
Code No. 6 - channel
unacceptable.
This cause indicates that
the channel most recently identified is not acceptable to the sending entity
for use in this call.
Code No. 7 - 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).
Code No. 8 - preemption.
This cause indicates the
call is being preempted.
Code No. 9 - 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.
Code No. 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.
What it means:
This could be almost anything; it is the vaguest of the cause codes. The call comes down normally, but the reasons for it could be:
1.
Bad username or password
2.
Router's settings do not match what is expected by the remote
end.
3.
Telephone line problems.
4.
Hung session on remote end.
Code No. 17 - 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.
What is means:
Calling end is busy.
Code No. 18 - 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.
What it means:
The equipment on the other end does not answer the call. Usually
this is a misconfiguration on the equipment being called.
Code No. 19 - no answer from
user (user alerted).
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.
Code No. 20 - 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.
Code No. 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. 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.
What it means:
This is usually a telco issue. The call never reaches the final
destination, which can be caused by a bad switch translation, or a
misconfiguration on the equipment being called.
Code No. 22 - 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, Code No. 1,
unallocated (unassigned) number shall be used.
Code No. 26 - non-selected
user clearing.
This cause indicates that
the user has not been awarded the incoming call.
Code No. 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 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.
Code No. 28 - invalid number
format (address incomplete).
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.
Code No. 29 - facilities
rejected.
This cause is returned when
a supplementary service requested by the user cannot be provide by the network.
Code No. 30 - 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.
Code No. 31 - normal.
unspecified.
This cause is used to report
a normal event only when no other cause in the normal class applies.
Code No. 34 - no
circuit/channel available.
This cause indicates that
there is no appropriate circuit/channel presently available to handle the call.
What it means:
There is no place on the Public Telephone network to place the
call; the call never gets to its destiation. This is usually a temporary
problem.
Code No. 35 - Call Queued.
Code No. 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.
Code No. 39 - 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)
Code No. 40 - 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.
Code No. 41 - temporary failure.
This cause indicates that
the network is not functioning correctly and that the condition is no likely to
last a long period of time; e.g., the user may wish to try another call attempt
almost immediately.
What it means:
This means that there is a temporary failure at the physical
layer on the ISDN network. If you remove the ISDN cable from the Netopia, you
would see this. It's usually temporary.
Code No. 42 - switching
equipment congestion.
This cause indicates that
the switching equipment generating this cause is experiencing a period of high
traffic.
What it means:
Just too much going on at this point on the ISDN network to get
the call through to its destination.
Code No. 43 - 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.
Code No. 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.
Code No. 46 - precedence
call blocked.
This cause indicates that
there are no predictable circuits or that the called user is busy with a call
of equal or higher preventable level.
Code No. 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.
Code No. 49 - 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).
Code No. 50 - 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.
What it means:
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.
Code No. 52 - outgoing calls
barred.
Code No. 53 - 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.
Code No. 54 - incoming calls
barred
Code No. 55 - 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.
Code No. 57 - 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.
Code No. 58 - 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.
Code No. 62 - inconsistency
in outgoing information element.
This cause indicates an
inconsistency in the designated outgoing access information and subscriber
class.
Code No. 63 - 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.
Code No. 65 - 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.
Code No. 66 - channel type
not implemented.
This cause indicates that
the equipment sending this cause does not support the channel type requested.
Code No. 69 - requested
facility not implemented.
This cause indicates that
the equipment sending this cause does not support the requested supplementary
services.
Code No. 70 - 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.
Code No. 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.
Code No. 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 user-network interface.
Code No. 82 - 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.
Code No. 83 - 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).
Code No. 84 - 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.
Code No. 85 - 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.
Code No. 86 - 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).
Code No. 87 - 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.
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.
Code No. 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.
What it means:
1.
This usually means that the Number To Dial in the Connection
Profile is in the wrong format. You may need to dial a 10 or 11 digit number,
or dial a 9 in front of the number if it is a Centrex line.
2.
This problem may also give a Cause 111.
3.
Dialing at the wrong line speed can also give this Cause.
Code No. 90 - non-existent
CUG.
This cause indicates that
the specified CUG does not exist.
Code No. 91 - invalid
transit network selection (national use).
This cause indicates that a
transit network identification was received which is of an incorrect format as
defined in Annex C/Q.931
Code No. 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.
Code No. 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.
What it means:
This is rarely seen in North America but usually means that the
number that is being dialed is in the wrong format, (similar to cause 88). Some
part of the format being used is not understood by either the remote side
equipment or the switching equipment between the source and destination of the
call.
Code No. 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 recognize either because this is a message not defined of defined but
not implemented by the equipment sending this cause.
Code No. 98 - 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.
Code No. 99 - 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.
Code No. 100 - 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.
What it means:
Like cause 1 and cause 88, this usually indicates that the ISDN
number being dialed is in a format that is not understood by the equipment
processing the call. SPIDs will sometimes fail to initialize with a Cause 100,
or a call will fail with this cause.
Code No. 101 - message not
compatible with call state.
This cause indicates that a
message has been received which is incompatible with the call state.
Code No. 102 - 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.
What it means:
This is seen in situations where ACO (Alternate Call Offering)
is being used. With this type of call pre-emption, the Telco switch operates a
timer. For example, when an analog call is placed to a Netopia router that has
two B Data Channels in place, the router relinquishes the second channel, but
if it doesn't happen in the time allotted by the switch programming, the call
will not ring through and will be discarded by the switch.
Code No. 103 - parameter
non-existent or not implemented - passed on (national use).
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.
Code No. 110 - 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.
Code No. 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.
Code No. 127 - Intel-working,
unspecified.
This cause indicates that an
interworking call (usually a call to 5W56 service) has ended.
Notes about Cause Codes over
128
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.
The PRI equipment vendors are the most likely to use these codes as they have been using proprietary messages in the facilities data link for some time now (there is an as yet undefined area in the FDL which is big enough to carry small datagrams or messages). It is typically used to pass proprietary control or maintenance messages between multiplexers.
The PRI equipment vendors are the most likely to use these codes as they have been using proprietary messages in the facilities data link for some time now (there is an as yet undefined area in the FDL which is big enough to carry small datagrams or messages). It is typically used to pass proprietary control or maintenance messages between multiplexers.