ISDN Software Reference for Linux and Windows
400
Billing info
(return
immediately.)
<--
cc_ReleaseCall(
)
-->
Call_Dealloc
-->
Return
<-- NULL CALL_DEALLOC_ACK
<--
Two B Channel Transfer (TBCT)TBCT enables an ISDN PRI user to request the switch to connect together two
independent calls on the user’s interface. The two calls can be served by the same
PRI trunk or by two different PRI trunks that both serve the user.
NOTE:
For more on TBCT, refer to the Bellcore Generic Requirements GR-
2865-CORE, ISSUE 2, May 1997: Generic Requirements for ISDN PRI
Two B Channel Transfer.
If the switch accepts the request, the user is released from the calls and the two
other users are connected directly. Billing for the two original calls continues in
the same manner as if the transfer had not occurred. As an option, TBCT also
allows for transfer notification to the transferred users.
TBCT works only when all of the following conditions are met:
• The user subscribes to TBCT (this feature is supported for 5ESS, 4ESS, and
NI2 protocols)
• The two calls are of compatible bearer capabilities
• At least one of the two calls is answered. If the other call is outgoing from the
user, it may be either answered or alerting; if the other call is incoming to the
user, it must be answered.
The TBCT feature is invoked by sending a FACILITY message to the Network
containing, among other things, the Call Reference Values (CRVs) of the two calls
to be transferred. The cc_GetNetCRV( ) function allows applications to query the
Dialogic firmware directly for the Network Call Reference Value. (See the
cc_GetNetCRV( ) function description in Chapter 5. ISDN Function Reference
for more information.)