Dialogic 6.2 Manuale Utente

Loop Start Signaling

November 2009

303

To configure a Brooktrout module for FXO loop start signaling, the 

host must issue an L4L3mENABLE_CAS with an IISDN_ROBBED_

BIT_DATA structure that contains the following settings:

„

send_glare_err_event = 0 (not used for loop start)

„

in_trunk_type = IISDNttFXO_LPSTART

„

out_trunk_type = IISDNttFXO_LPSTART

„

timed_answer_supervision = 0 (answer supervision required)

„

fgb_fgd_mode = 0 (not used)

The remaining settings are described in the context of incoming and 

outgoing calls in the subsections that follow.

The FXO end of a loop start connection uses the same A and B 

bit values for both idle and connected states. Because of this, 

the Brooktrout module cannot detect when the FXO end goes 

on hook. To idle the channel, the host must detect the presence 

of a busy/reorder tone coming from the FXO end and issue an 

L4L3mCLEAR_REQUEST to disconnect the call. To ensure 

the FXO end returns to an idle state, the host must also reset 

the channel by issuing an L4L3mDISABLE_CAS immediately 

followed by an L4L3mENABLE_CAS in order to make another 

call.