Nortel Media Gateway 3200 User Manual page 316

When MFC/R2 protocol is used, the two detectors (opened by default) are the Call
Progress Tones and MFC/R2 Forward MF. When the User invokes outgoing call via
acPSTNPlaceCall(), MFC/R2 Forward MF detector is replaced with MFC/R2
Backward MF detector, since only two detectors per DSP channel are permitted to
operate simultaneously.
The correct MF is automatically generated according to the call direction - Forward for
outgoing calls and Backward for incoming calls.
MFC/R2 protocol fault could cause a channel block. In this case, the script file
provided by Nortel releases the call to enable the User to free the call resources and
be notified about being in blocking state.
START_COLLECT and STOP_COLLECT must be used in the script file for MF
collecting both in outgoing and incoming calls. Warning: If this script function isn't
used, the script gets stuck and forward\backward MF are not detected.
The Ringback Call Progress Tone is translated to a unique event
acEV_PSTN_ALERTING, since the Ringback tone is actually used in all Nortel
protocols' state machines. All other Call Progress Tones are conveyed via the
acEV_TONE_DETECTED, and retrieved by the User according to their type and index
(note that the Ringback tone should be defined in the Call Progress Tones table with
the relevant type in order to get this event).
When the tone detection event is received, Users can perform any action. For
example, if the event is received with BUSY tone indication, Users can invoke
acPSTNDisconnectCall() to end the call.
The MFR2 destination number is collected using:
EXPECTED_NUM_OF_DIGITS_MINUS_1 parameter for SET_COUNTER that the
User defines at UserProt_defines_R2_MF.h. The counter function is used to trigger
the script file for the last-but-one received, after receiving the last digit, the script file
(acting as the outgoing register) initiates the A6/A3 FWD MF. Normally variant
supports end of digit information (MF15) or silence at the end of the dialing (when
MF15 is not used), a short pulse of MF3 (A3) is sent to indicate that the entire string of
digits (according to Q442, 476) is received.
Sending Group B digit by an incoming register requires invoking acCASAcceptCall()
with a certain reason parameter. Six reason parameters are available:
CALLED_IDLE - Subscribers line is free. Continue the call sequence. Usually should
be followed by accept or reject.
1. CALLED_BUSY - Subscriber line is busy. Perform disconnect procedures.
2. CALLED_CONGESTION - Congestion encountered. Perform disconnect
procedures.
3. CALLED_UNALLOCATED - Dial number was not allocated. Perform disconnect
procedures.
4. CALLED_RESERVE1 - Reserved for additional group B (user additional
requirements).
5. CALLED_RESERVE2 - Reserved for additional group B (user additional
requirements).
Each reason generates a specific action, defined by the User, who modifies the script
file. The action is then used to generate/respond with a group B MF (free, busy, etc.).
User's Manual 316
MG 3200
Document # LTRT-72704