Filter
Top Products
Loop Start Signaling
November 2009 304
Incoming Call Processing
During an incoming call, the host receives an L3L4mPRE_SEIZE
message if send_preseize_event = 1 in the IISDN_ROBBED_BIT_
DATA structure. This message is sent when the module detects an
incoming seize from the far end (FXS end). The module then collects
dial pulse digits from the network; the maximum number of digits
the module expects to receive must be specified in the max_
incoming_digit_count field. The digits are reported to the host in an
L3L4mSETUP_IND message. To answer the call, the host must
issue an L4L3mCONNECT_REQUEST message. Figure 39 shows
how a Brooktrout module processes an incoming call received over
an FXO loop start trunk.
Outgoing Call Processing
During an outgoing call, the host receives an L3L4mPROGRESS in
response to the L4L3mCALL_REQUEST to start the call. The
module automatically transmits a ringing pattern using the B
signaling bit. When the far end goes off hook, the host receives an
L3L4mCONNECT indicating the call is connected.
Figure 40 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 41; for an outgoing
call teardown, refer to Figure 42.