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Ground Start Signaling
November 2009 292
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 host
then receives an L3L4mSEIZE_COMP message if send_seize_comp_
event = 1 in the IISDN_ROBBED_BIT_DATA structure. This
message is sent after the fixed pause timer expires. No digits are
collected in FXO ground start mode; the module simply 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 32 shows how the module makes an outgoing call over an
FXO ground start trunk.
Call Teardown Processing
For an incoming call teardown, refer to Figure 33; for an outgoing
call teardown, refer to Figure 34.