User guide

116 RealCT Direct API Developer Guide
Chapter 4: E1 Networking
In the early stages of development, it might be hard to tell if the
application fails to call RHT_OFF_HOOK. 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 call is suddenly terminated. If your application
consistently 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.