Nortel DMS-250 - Page 113

Call control procedures 5-41
Digital Switching Systems DMS-250 ISDN Reference Manual MWC14 (CSP14)
Figure 5-23
User initiates call clearing, timer expires
Network
User
DISC
Network frees the NETWORK
connection. The trunk member is
and the T308 and lockout timers
Lockout timer expires, so trunk
is put in lockout state.
idled, the B-channel is disconnected,
are started.
T308 expires. Start T308 again.
T308 expires. Release call reference
but not B-channel until restart
procedure is invoked. Trunk
remains in lockout state.
REL
REL
Network-initiated call clearing
Figure 5-24 shows how the network initiates call clearing.
Figure 5-24
Network initiates call clearing, timer expires
Network
User
DISC
Network frees the NETWORK
connection. The trunk member is
and the T305 and lockout timers
Lockout timer expires, so trunk
is put in lockout state.
idled, the B-channel is disconnected,
are started.
T305 expires. Start T308.
Cancel T308, release the
B-channel and call reference,
and put the trunk member back
to idle state.
REL
REL COM
If the lockout timer expires before a REL message is received, the network
puts the trunk member in lockout state. If timer T305 expires before a REL