5-14 Call control procedures
297-2521-106 Standard 23.01 March 2001
•
CONN message—If the network receives an indication from the
outgoing trunk that the far end has answered, a CONN message is sent
out over the originating PRI interface. The originator responds with
CONN ACK. (The user receives a CONN ACK in response to a CONN
sent to the network.)
Figure 5-6 shows the message sequence between the network and the
originating PRI interface when the terminator is a non-ISDN trunk.
Figure 5-6
Q.931 message sequence for PRI-to-non-ISDN trunk call setup
Originating
user
Network
Terminating
PTS trunk
SETUP (CR,CID, BC, NSF,CDN,CGN,
DIE, OCN, RGN)
CALL PROC
(Translations and routing complete)
Network terminates call on non-
B-channel cut-through
Trunk returns answer supervision
CONN
(Billing starts)
CONN ACK
ISDN trunk.
PROG
(PI = call not end-to-end ISDN)
when called party answers.
Note: Dashed lines indicate optional messages.
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