2024年3月28日发(作者：)

ITU-T

Q.850

Code

EnumerationCause

may be generated by the called

user or by the network. In the

case of user determined user

Description

busy it is noted that the user

equipment is compatible with the

call.

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.

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.

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. Sofia

SIP will normally raise

USER_NOT_REGISTERED in

such situations.

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. The

network may also generate this

cause, 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.

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, cause no:

1, unallocated (unassigned)

number shall be used.

This cause is used by a general

ISUP protocol mechanism that

can be invoked by an exchange

that decides that the call should

be set-up to a different called

number. Such an exchange can

invoke a redirection mechanism,

by use of this cause value, to

request a preceding exchange

involved in the call to route the

call to the new number.

18408NO_USER_RESPONSEno user responding [Q.850]

19480NO_ANSWER

no answer from user (user alerted)

[Q.850]

20480SUBSCRIBER_ABSENTsubscriber absent [Q.850]

21603CALL_REJECTEDcall rejected [Q.850]

22410NUMBER_CHANGEDnumber changed [Q.850]

23410REDIRECTION_TO_NEW_DESTINATION