5-24 Call control procedures
297-2521-106 Standard 23.01 March 2001
for permanent signaling and PARTDIAL for partial dial. The DMS-250
switch ignores any digits dialed after a timeout.
The DMS-250 switch also ignores the DTMF signals * and #; these digits
cannot reset the timeout periods for partial dial or permanent signaling.
After receiving the suppcode, the DMS-250 switch stores it in the parameter
AUTHCC3 of the CDR for non-VNET calls and in the PNR for VNET calls.
Call takedown for normal call clearing
The procedures for call takedown when normal call clearing is initiated (by
either the user or the network) are described as follows.
A normal disconnect sequence consists of three messages:
• DISC—The first message is always a DISC message, whether the user or
the network initiates call clearing of an established call.
• REL—The other end of the connection responds with this message.
• REL COM—The side initiating call clearing responds with this message.
User-initiated normal call clearing
When the network receives the DISC message from the user over a PRI
trunk, this is equivalent to detecting an on-hook signal on a PTS trunk.
Eventually, the network idles the PRI trunk member by disconnecting the
B-channel. The channel remains unavailable for any other calls.
As shown in Figure 5-14, the network responds to the DISC message by
• starting timer T308
• starting a DMS-250 switch internal lockout timer
• sending a REL message to the user
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