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OPERATION LBI-39076
B
39
IDENTIFYING CALLED ID
13. The channel-terminating GTI detects the first DTMF
digit, momentarily lights the “DTMF DETECTED” red
LED on the front panel, and reports the digit to the Site
Controller.
14. The Site Controller directs the line-connected GTI to
stop sending a dial tone to the calling line, and starts a
counter to count the received DTMF digits.
15. The Site Controller checks the first DTMF digit to see if
it is a #, *, or number from 0 to 9.
If the first DTMF digit is a #, the call is identified as a
digital call, but the counter is not advanced. (The call
will be assigned but audio will be incorrect. This is
because ELI does not support digital mode.)
If the first DTMF digit is a * (or a 9 when using pulse
dialing), the call is identified as a group call, and the
counter is advanced by one.
If the first DTMF digit is a number from 0 to 8, the digit
is stored in the ID buffer and the counter is advanced by
one.
16. The channel-terminating GTI detects the next DTMF
digit, momentarily lights the “DTMF DETECTED” red
LED on the front panel, and reports the digit to the Site
Controller.
17. The Site Controller receives the report from the
channel-terminating GTI, stores the digit in its ID
buffer, advances the counter by 1, and checks to see if
the counter has reached 5. If the Site Controller is still
within the DTMF Digit Detect Duration and the counter
has not reached 5, return to step 16.
If the counter has not reached 5 within the 20 second
DTMF Digit Detect Duration, the Site Controller will
send a message to the channel-terminating GTI
instructing it to send the call denied tone or voice
prompt, and hang up. This ends the sequence here.
18. If the counter has reached 5, the Site Controller has now
received all digits of the called ID, and directs the
channel-terminating GTI to stop looking for DTMF
digits and disconnect the audio connection from the
line-connected GTI.
19. The Site Controller checks to see if the called ID is
valid, and if the ID is allowed to receive interconnect
calls. (See Inb Interconnect field in System Manager
screen 11, panel 2.)
If the called ID is not valid, or is not
allowed to receive
interconnect calls, the Site Controller sends a message
to the line-connected GTI instructing it to send the call
denied tone (or voice prompt) and hang up. This ends
the sequence here.
OBTAINING WORKING CHANNEL
20. If the called ID is valid and is
allowed to receive
interconnect calls, the Site Controller checks to see if a
working channel with a channel-terminating GTI is
available.
If a working channel with a channel-terminating GTI is
not currently available, the Site Controller queues the
call and instructs the GTI to apply a queue tone (or
voice prompt) to the line. When the call comes out of
the queue, continue to next step.
21. If a Working Channel with a channel-terminating GTI is
available, the Site Controller sends a message to the
Control Channel GETC to send the Working Channel
assignment to the radio(s) with the called LID or GID.
22. The radio(s) with the called LID or GID receive(s) the
Working Channel assignment and tune(s) to the
assigned Working Channel.
23. The Site Controller sends a message directing the
channel-terminating GTI to insert itself into the audio
loop of the assigned Working Channel in preparation
for a telephone interconnect call.
24. The Site Controller sends a message directing the
channel-connected GTI to apply a ringing tone to the
called radio(s) and the line-connected GTI unit to apply
a ringback tone to the calling telephone.
25. A radio user hears the ringing tone and pushes the PTT
switch.
26. The assigned Working Channel GETC detects the radio
transmission on the assigned Working Channel and
sends a radio keyed message to the Site Controller. If
the Site Controller does not receive this message within
the Interconnect Hang Time (see System Manager
screen 10, panel 2.), it sends a hang up message to the
line-connected GTI and a disconnect message to the
Working Channel GETC.
27. If the Site Controller receives the radio keyed message
within Interconnect Hang Time, it sends a connect
audio message to the Master GTI. The Master GTI
directs the line-connected GTI and channel-connected
GTI to send the digitized audio to each other over the