Dialogic 6.2 - Manual (Page 298)

Ground Start Signaling
November 2009 298
Outgoing Call Processing
If send_glare_err_event = 0 in the IISDN_ROBBED_BIT_DATA
structure, the host receives an L3L4mERROR message containing
the value L3L4errGLARE if the outgoing call attempt fails due to
glare. Glare occurs when the module attempts to make an outgoing
call on a channel at the same time an incoming call arrives on the
channel. The call attempt fails because the network always wins
channel contention.
During an outgoing call, the host receives an L3L4mPROGRESS in
response to the L4L3mCALL_REQUEST to start the call. The
module starts the fixed pause timer when it detects tip ground at the
far end (FXO end). When the timer expires, the host receives an
L3L4mSEIZE_COMP message if send_seize_comp_event = 1 in the
IISDN_ROBBED_BIT_DATA structure.
FXS ground start supports transmitting digits other than dial pulse
digits. If called_party_digits = 0 in the L4L3mCALL_REQUEST that
started the call, the module waits in outdialing state indefinitely.
During that time, another device connected to the Brooktrout
module over the TDM bus (such as a digital tone generator) is used
to outpulse digits to the network.
After the digits are transmitted, the module waits for an answer
timer to expire (if timed_answer_supervision = 1). When the timer
expires, the host receives an L3L4mCONNECT indicating the call is
connected.
Figure 36 shows how the module makes an outgoing call over an
FXS ground start trunk.
Call Teardown Processing
For an incoming call teardown, refer to Figure 37 ; for an outgoing
call teardown, refer to Figure 38 .