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Title: Understand Voice Router Internal Call Disconnect Cause Code Table
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Understand Voice Router Internal Call Disconnect
Cause Code Table
Contents
Introduction
Prerequisites
Requirements
Components Used
Background Information
Internal Cause Code Table
Introduction
This document describes the well-known Q.850 cause code values.
Prerequisites
Requirements
There are no specific requirements for this document, however, knowledge of SIP and H.323 is preferred.
Components Used
This document is not restricted to specific software and hardware versions.
The information in this document was created from the devices in a specific lab environment. All of the
devices used in this document started with a cleared (default) configuration. If your network is live, ensure
that you understand the potential impact of any command.
Background Information
Each Session Initiation Protocol (SIP) and H.323 standard cause code accurately reflect the nature of the
associated internal failure. This capability makes the H.323 and SIP call-control protocols consistent with
cause codes that are generated for common problems. For each of the failures listed, the standard category is
associated with a standard category description, the Q.850 cause code value, and a description of this value.
Internal Cause Code Table
Standard
Category
Standard Category
Description
Q.850
Cause
Code
Q.850 Release Cause Description
Unallocated
The typical scenarios
Indicates that the destination requested by the calling party
1
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(unassigned)
number
include situations
where the number is
not present in the
routing table, or
when there is no
available path
through the ISDN
network.
cannot be reached because the number is unassigned.
No route to a
specified transit
network
(national use)
Typical scenarios
include:
A wrong
transit network
code was
dialed.
•
The transit
network does
not serve this
equipment.
•
The transit
network does
not exist
•
2
Indicates that the gateway is asked to route the call through an
unrecognized intermediate network.
Destination
address
resolution
failure
Typical scenarios
include:
Domain Name
System (DNS)
•
Invalid session
target in
configuration
•
3
CC_CAUSE_NO_ROUTE
Indicates that the called party cannot be reached because the
network that the call has been routed through does not serve the
desired destination.
Send special
information tone
The typical scenario
includes the dialed
number that has a
special condition
applied to it.
4
Indicates that the called party cannot be reached for reasons that
are of a long-term nature and that the special information tone
must be returned to the calling party.
Misdialed trunk
prefix (national
use)
The typical scenario
includes the wrong
trunk prefix was
dialed.
5
Indicates the erroneous inclusion of a trunk prefix in a called
party number.
Channel
Unacceptable
The typical scenario
is failed channel on
the network.
6
Indicates that the channel most recently identified is not
acceptable to the sending entity for use in this call.
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Call awarded
and delivered in
an established
channel
The typical scenario
is a successful call.
7
Indicates that the called party has been awarded the incoming
call and that the incoming call is connected to a channel already
established with that called party for similar calls.
Preemption
The typical scenario
is for emergency
services.
8
Indicates the call is preempted.
Preemption;
Circuit reserved
for reuse
The typical scenario
is for emergency
services.
9
Indicates the call is preempted and the circuit is reserved for
reuse by a preempting exchange.
Normal call
clearing
The typical scenario
is a call
participant hung up.
16
Indicates that the call was cleared because one of the parties
involved with the call has requested that the call be cleared.
User busy
The typical scenario
is the user is already
on the telephone.
17
Indicates that the called party is unable to accept another call
because the busy condition of the user has been encountered.
This cause value can be generated by the called party or by the
network. In the case when the called party determined the user is
busy, it is noted that the called equipment is compatible with the
call.
No user
responding
The typical scenario
is the user did not
answer the
telephone.
18
Used when the called party does not respond to a call
establishment message with either an alerting or connect
indication within the time allotted. The number that was dialed
has an active D-channel, but the far end chooses not to answer.
No answer from
the user (user
alerted)
The typical scenario
is the user did not
answer the
telephone.
19
Used when the called party has been alerted but does not respond
with a connect indication within the time allotted. This cause is
not generated by Q.931 procedures but can be generated by
internal network timers.
Subscriber
Absent
The typical scenario
is the user lost
network
connectivity or is out
of range.
20
Used when a mobile station has logged off, radio contact is not
obtained with a mobile station, or if a personal
telecommunication party is temporarily not addressable at any
network interface.
Indicates that the equipment that sent this cause code does not
wish to accept this call, although it can accept the call because
the equipment that sent the cause is neither busy nor
incompatible.
Can also be generated by the network which indicates that the
Call Rejected
The typical scenario
is the subscriber has
a service constraint
that does not accept
this call.
21
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call was cleared because of a supplementary service constraint.
The diagnostic field can contain additional information about the
supplementary service and the reason for rejection.
Number
Changed
The typical scenario
is a subscriber has
changed their
number.
22
Returned to a calling party when the called number indicated by
the calling party is no longer assigned. The new called party
number can be optionally included in this diagnostic field.
Redirection to a
new destination
The typical scenario
is the call is
forwarded.
23
Used by a general ISUP protocol mechanism that decides that the
call must be sent to a different called number.
Exchange
routing error
The typical scenario
is the network is
overloaded.
25
Indicates that the destination indicated by the calling party
cannot be reached because an intermediate exchange has released
the call because it reached a limit in the execution of the hop
counter procedure.
Nonselected
user clearing
The typical scenario
is a called number
failure.
26
Indicates that the called number has not been awarded the
incoming call.
Socket failure
Typical scenarios
include:
Transmission
Control
Protocol
(TCP) socket
connection
failure.
•
Problem
sending an
H.323 SETUP.
•
Problem
sending a SIP
INVITE.
•
Send or
receive error
occurs on the
connected
socket.
•
27
CC_CAUSE_DESTINATION_OUT_OF_ORDER
Indicates that the destination indicated by the originator cannot
be reached because the interface of the destination does not
function correctly.
The signaling message cannot be delivered to the remote party.
The typical scenario
is the caller is calling
with the use of a
Invalid number
format
28
Indicates that the called party cannot be reached because the
called party number is not in a valid format or is not complete.
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network-type
number (enterprise)
rather instead of an
Unknown or
National.
Facility rejected
The typical scenario
is a network service
is not in function.
29
Indicates that a supplementary service requested by the
originator cannot be provided by the network.
Response to
STATUS
ENQUIRY
The typical scenario
is a STATUS
message is returned.
30
Included in the STATUS message when the reason for the
STATUS message was the prior receipt of a STATUS
ENQUIRY message.
Normal,
Unspecified
The typical scenario
is a normal
Operation.
31
Reports a normal event only when no other cause in the normal
class applies.
No
circuit/channel
available
The typical scenario
is no B-channels are
available to make the
selected call.
34
Indicates that there is no appropriate circuit or channel presently
available to handle the call.
Network out of
order
The typical scenario
is a network failure. 38
Indicates that the network does not function correctly and that
the condition is likely to last for an extended period.
The permanent
frame mode
connection is
out of service
The typical scenario
is equipment or
section failure.
39
Included in a STATUS message to indicate that a permanently
established frame mode connection is out of service.
The permanent
frame mode
connection is
operational
The typical scenario
is normal operation. 40
Included in a STATUS message to indicate that a permanently
established frame mode connection is operational and capable to
carry call information.
Temporary
failure
The typical scenario
is a network failure. 41
Indicates that the network does not function correctly and that
the condition is likely to be resolved quickly.
Switching
equipment
congestion
The typical scenario
is high traffic.
42
Indicates that the switching equipment that generates this cause
experiences high traffic.
Access
The typical scenario
Indicates that the network was not able to deliver access
43
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information
discarded
is usually reported
when the far-end
ISDN switch
removes some piece
of information
before tandem-
switching a call.
information to the called party as requested.
The requested
circuit/channel
is not available
The typical scenario
occurs during glare
conditions when
both sides are
selected top-down or
bottom-up. Change
the Allocation
Direction so that one
end is top-down and
the other is bottom-
up.
44
Returned when the circuit or channel indicated by the requested
entity cannot be provided by the other side of the interface.
Precedence call
blocked
The typical scenario
is a caller that is
busy and the priority
level of active call is
equal to or higher
than the incoming
call.
46
Indicates that there are no preemptive circuits or that the called
party is busy with a call of equal or higher preemptable level.
Internal resource
allocation failure
Typical scenarios
include:
Out of
memory
•
Internal access
to the TCP
socket is
unavailable
•
47
CC_CAUSE_NO_RESOURCE
Indicates a resource unavailable event.
QoS Error
The typical scenario
is a Quality of
Service (QoS) error.
49
CC_CAUSE_QOS_UNAVAILABLE
Indicates that the requested QoS cannot be provided.
The requested
facility is not
subscribed
The typical scenario
is the caller tries to
use a service that is
not permitted.
50
Indicates that the party has requested a supplementary service
that it is not authorized to use.
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Outgoing calls
barred within
Closed User
Group (CUG)
The typical scenario
is a subscriber
configuration
contains this
limitation.
53
Indicates that although the calling party is a member of a CUG
for the outgoing CUG call, outgoing calls are not allowed for this
member of the CUG.
Incoming calls
barred within
Closed User
Group (CUG)
The typical scenario
is the subscriber
configuration
contains this
limitation.
55
Indicates that although the called party is a member of a CUG for
the incoming CUG call, incoming calls are not allowed for this
member of the CUG.
Bearer
capability not
authorized
The typical scenario
is the caller is not
authorized to use the
bearer capability.
57
Indicates that the party has requested a bearer capability which is
implemented on the equipment but is not authorized to be used.
Bearer
capability not
presently
available
The typical scenario
is a call is placed
with a bearer
capacity that the
service provider does
not have the capacity
to supply.
58
Indicates that the party has requested a bearer capability which is
implemented by the equipment and is currently unavailable.
Inconsistency in
designated
outgoing access
information and
subscriber class
The typical scenario
is a network error.
62
Indicates that there is an inconsistency in the designated
outgoing access information and subscriber class.
Service or
option not
available,
unspecified
The typical scenario
is the service is not
available.
63
Reports a service or option not available event only when no
other cause in the service or the option not available class
applies.
Media
Negotiation
Failure
Typical scenarios
include:
No codec
match
occurred.
•
H323 or H245
problem that
leads to failure
in media
negotiation.
•
65
CC_CAUSE_BEARER_CAPABILITY_NOT_IMPLEMENTED
Indicates that the equipment that sent this cause does not support
the bearer capability requested.
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Channel type
not implemented
The typical scenario
is channel type
match is not found.
66
Indicates that the equipment that sent this cause does not support
the channel type requested.
The requested
facility is not
implemented
The typical scenario
is service type match
is not found.
69
Indicates that the equipment that sent this cause does not support
the requested supplementary service.
Only restricted
digital
information
bearer capability
is available
(national use)
The typical scenario
is a routing error.
70
Indicates that the calling party has requested an unrestricted
bearer service but that the equipment that sent this cause only
supports the restricted version of the requested bearer capacity.
Service or
option not
implemented,
unspecified
The typical scenario
is a service is not
implemented.
79
Reports a service or option not implemented event only when no
other cause in the service or option not implemented class
applies.
Invalid call
reference value
The typical scenario
is the far-end switch
did not recognize the
call reference for a
message sent by the
gateway.
81
Indicates that the equipment that sent the cause has received a
message with a call reference that is not currently in use on the
user-network interface.
The identified
channel does not
exist
The typical scenario
is a fractional PRI
error.
82
Indicates a call was attempted on a channel that is not
configured.
A suspended
call exists, but
this call identity
does not
The typical scenario
is a call ID
mismatch.
83
Indicates a call resume has been attempted with a call identity
that differs from that in use for any presently suspended calls.
Call identity in
use
The typical scenario
is equipment error.
84
Indicates that the network has received a call suspended request
that contains a call identity that is already in use for a suspended
call.
No call
suspended
The typical scenario
is equipment error.
Indicates that the network has received a call resume request that
contains a call identity information element that does not indicate
any suspended call.
The call that has Typical scenarios
Indicates that the network has received a call identity
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the requested
call identity has
been cleared
include:
Network
timeout
•
The call is
cleared by a
remote user
•
SIP UAC
sends a request
to UAS with
no response
•
information element that indicates a suspended call that has in
the meantime been cleared wile suspended.
The user is not a
member of
Closed User
Group (CUG)
The typical scenario
is the caller is not
authorized.
87
Indicates that the called user for the incoming CUG call is not a
member of the specified CUG.
Incompatible
destination
Typical scenarios
include:
The number
dialed is not
capable of this
type of call.
•
The caller is
calling a
restricted line
in unrestricted
mode.
•
The caller is
calling a
POTS phone
with the use of
an unrestricted
mode.
•
88
Indicates that the equipment that sent this cause has received a
request to establish a call that has compatibility attributes that
cannot be accommodated.
Nonexistent
Closed User
Group (CUG)
The typical scenario
is a configuration or
dialing error.
90
Indicates that the specified CUG does not exist.
Invalid transit
network
selection
(national use)
Typical scenarios
include:
Network error
•
Identification
mismatch
•
91
Indicates that a transit network identification was received which
is of an incorrect format.
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Invalid message
error received
The typical scenario
is an invalid message
was received.
95
CC_CAUSE_INVALID_MESSAGE
Indicates an invalid message event.
Mandatory IE
missing error
Typical scenarios
include:
Mandatory
Contact field
missing in the
SIP message.
•
The Session
Description
Protocol
(SDP) body is
missing.
•
96
CC_CAUSE_MANDATORY_IE_ MISSING
Indicates that the equipment that sent this cause code has
received a message that is missing an information element (IE).
This IE must be present in the message before the message can
be processed.
Message type
nonexistent or
not implemented
The typical scenario
is that message-type
information is
missing.
97
Indicates that the equipment that sent this cause has received a
message which is missing an information element that must be
present in the message before the message can be processed.
Message not
compatible with
call state or
message type
nonexistent or
not implemented
Typical scenarios
include:
ISDN protocol
mismatch
•
ISDN state
machine
violation
•
98
Indicates that the equipment that sent this cause has received a
message such that the procedures do not indicate that this is a
permissible message to receive while in this call state.
An information
element or
parameter does
not exist or is
not implemented
The typical scenario
is an element
mismatch.
99
Indicates that the equipment that sent this cause has received a
message which includes information elements or parameters not
recognized because the information element or parameter names
are not defined or are defined but not implemented by the
equipment.
Invalid IE
contents error
The typical scenario
is a SIP contact field
is present, but the
format is bad.
100
CC_CAUSE_INVALID_IE_ CONTENTS
Indicates that the equipment that sent this cause code has
received an IE that it has implemented. However, the equipment
that sent this cause code has not implemented one or more of the
specific fields.
The typical scenario
is an unexpected
message was
CC_CAUSE_MESSAGE_IN_INCOMP_CALL_STATE
Indicates that a message has been received that is incompatible
Message in the
invalid call state
101
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received that is
incompatible with
the call state.
with the call state.
Call setup
timeout failure
Typical scenarios
include:
No H.323 call
proceeding
•
No H.323
alerting or
connect
message was
received from
the terminating
gateway
•
SIP Invite
expires timer
reached the
maximum
number of
retries allowed
•
102
CC_CAUSE_RECOVERY_ON_ TIMER_EXPIRY
Indicates that a procedure has been initiated by the expiration of
a timer in association with procedures that handle errors.
Parameter
nonexistent or
not implemented
passed on
(national use)
The typical scenario
is a configuration
mismatch.
103
Indicates that the equipment that sent this cause has received a
message which includes parameters not recognized because the
parameters are not defined or are defined but not implemented on
the equipment.
A message with
an unrecognized
parameter
discarded
The typical scenario
is an unrecognized
parameter.
110
Indicates that the equipment that sent this cause has discarded a
received message which includes a parameter that is not
recognized.
Protocol error,
unspecified
The typical scenario
is a protocol error.
111
Reports a protocol error event only when no other cause in the
protocol error class applies.
Internal error
The typical scenario
is a device failed to
send a message to
Public Switched
Telephone Network
(PSTN).
127
CC_CAUSE_INTERWORKING
Indicates that there has been interworking with a network that
does not provide causes for actions it takes. The exact cause
cannot be ascertained.