4-10 Message structure and function
297-2521-106 Standard 23.01 March 2001
Table 4-1
Q.931 message descriptions
(continued)
Message Event informationDirectionMeaning
CONN Connect Sent by the called party to the
network, and by the network
to the calling party, to indicate
call acceptance by the called
party.
Generated by the terminating
side of the call when the call is
answered. This message is
sent from the terminator to the
network. The network
subsequently sends a CONN
message back to the originator.
Billing begins at this time.
CONN ACK Connect
acknowledge
Of local significance; sent by
the network to the called party
(and may optionally be sent
by the calling party to the
network) in response to a
CONN message.
After the originator receives the
CONN message, it responds
back to the network with a
CONN ACK message. The
network also responds to the
terminator with a CONN ACK
message.
DISC Disconnect Sent by either the calling party
or the network as an invitation
to release the channel and
call reference. The channel
and call reference are
retained.
Generates when one member
of the call hangs up. This
message is equivalent to
detecting an onhook signal on
a PTS trunk. This is the first
step in the call takedown
message sequence. Billing is
now complete.
FAC ACK Facility
acknowledge
Sent by either the called user
or the network to the calling
user.
Indicates acceptance of the
user-to-user feature and ability
to receive the USER INFO
message.
FAC REJ Facility reject Sent by either the called user
or the network to the calling
user.
Sent when resources are not
available to accept the USER
INFO message or when the
user-to-user feature is not
supported.
—continued—
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