User guide

August 2001 63
Handling Incoming and Outgoing Calls
In Wink Start, Double Wink Start, and Immediate start
protocols, the audio path is established soon after the CO sends
digits so the remote end can hear the control tones. With the
audio path established, the remote end will also hear any files
the application plays even if the application fails to call
RHT_OFF_HOOK. If the CO does not receive the answer signal,
however, it times out within two to four minutes and terminates
the call. To the application and the caller, it appears that the
call was being handled properly until the line suddenly
disconnected. If your application reports that it received a
disconnect after two to four minutes while it was processing the
call, check to be sure the application called RHT_OFF_HOOK to
answer the call.
If you are sure that your application called RHT_OFF_HOOK,
consider the other extreme. The application might call
RHT_OFF_HOOK too soon after it detects digits. In this case
the switches down the path might not be ready to receive the
answer signal, so they do not detect it. The application should
send control tones after receiving digits so the COs in the path
are ready to receive the answer signal.