Dialogic 6.2 - Manual (Page 205)

Transferring Calls Using Release Link Trunk Transfer
November 2009 205
The call is transferred by the board, but it must maintain active call
setup on both B-channels for the duration of the call.
RLT Call Transfer
ALERTING <=== L4L3mALERTING (B1) Now that B-channel #2 is set up, continue
with normal call setup on B1, sending
alerting and connect.
CONNECT <=== L4L3mCONNECT (B1)
Network Host
SETUP ===> L3L4mSETUP_IND (B1) The host receives an incoming call on
B-channel #1. From the
IISDN_CALLED_PARTY info, the host
application determines this call needs to be
rerouted to an alternate branch office.
SETUP <=== L4L3mCALL_REQUEST (B2)
rtl_service = 1
The host initiates outbound call on B2,
setting the rlt_service flag to ‘1’.
ALERTING ===> L3L4mALERTING (B2)
includes 0x1c (FACILITY) IE with
call_id.
The network sends an ALERTING message
with the FACILITY info element containing
the call ID for the second link.
CONNECT ===> L3L4mCONNECT (B2)
FACILITY <=== L4L3mFACILITY_REQUEST The host initiates the transfer and release
process by sending a FACILITY message.
The call_ref and l4_ref parameters of the
initial (B1) call sends a
L4L3mFACILITY_REQUEST message,
and the application populates the
IISDN_CALL_ID field with the call_id
information retrieved from the ALERTING
message of the second call (B2).