User guide

124 RealCT Direct API Developer Guide
Chapter 4: E1 Networking
Glare Resolution
If the line is not idle when the application calls
RHT_SEIZE_LINE
, BrktGetLastError (DeviceHandle), returns
BRKT_ERROR_CODE(IO_DEVICE). See Troubleshooting on page 134
for more information on how to handle the error.
It is possible for the application to try to seize the line as the CO
tries to send a call. In this situation, called a glare,
RHT_SEIZE_LINE returns an error but does not set the line
back to idle. In order to accept the incoming call, the application
calls RHT_OFF_HOOK. If it does not accept the call, it calls
RHT_DISCONNECT to set the line back to idle. Check with
your carrier to see how they want applications to handle glare
situations (also called glare resolution).
Sending Call Setup Information
After the application seizes the line, it transmits call setup
information using RHT_DIAL_R2. Call setup is usually done
using R2-MF tones, also called MFC. RHT_DIAL_R2 handles
all aspects of the compelled protocol.
While dialing, the application monitors the line by setting field
‘LineTerm0’ in the VPdialR2_s structure as described in
Monitoring For Disconnection on page 117.
If the function returns successfully, the application monitors
the call for answer. If the function returns
T_RHT_LINEOFF, then
the function terminated because of a line condition. Call
RHT_GET_STATUS to find out what line condition occurred.
Other codes indication more serious error conditions. You
should abandon the call using RHT_DISCONNECT and try the
call again.
For more information about how E1 applications dial digits, see
Chapter 2, Digit Handling, on page 15.