Printed in the U.S.A. ZF290220 Rev CFax Back Doc # 675
Due to the dynamic nature of the product design, the information contained in this document is subject to change without notice. Viking
Electronics, its affiliates and/or subsidiaries assume no responsibility for errors and/or omissions contained in this information. Revisions of
this document or new editions of it may be issued to incorporate such changes.

Product Support Line...(715) 386-8666 Fax Back Line...(715) 386-4345

Operation
A control phone connected directly to the MLC-24’s “control line” controls the lamps. The "control line" may also be
connected to a C.O. line, analog PABX/KSU station, or an unused C.O. port.

C. Message Waiting Lamp Illumination

1. Neon Message Waiting Phones and/or LM-1 Modular Message Waiting Lamp Retrofit Kit
This kit will illuminate when the receiver is on-hook. They will go out when the receiver is off-hook and go on as
the receiver is returned on-hook. The lamp may be extinguished by an off Touch Tone code or by momentarily
(.25 - 2 seconds) going off hook.
2. LM-2 LED Message Waiting Lamp Kit
This kit will illuminate immediately and remain on until the LM-2 switch is depressed momentarily (.25 - 2
seconds) or an off Touch Tone code is issued to extinguish the LED.
3. LED’s
These will illuminate immediately and remain on until an “off” Touch Tone code is issued to extinguish the LED.

D. Power Failure

In the event of AC power failure, the message waiting lamps will not function. All telco operations will operate as
normal.

E. Special Features

1. With switch positions 1 and 3 in the OFF position and 2 and 4 in the ON position, the display will indicate on or
off hook condition for 24 lines (off-hook = LED is on, on-hook = LED is off).
Note: Depress the reset button on
the MLC-24 after changing switch positions.

A. On Premise Operation

When the MLC-24 is connected to a station circuit of a
PABX, the voice mail system or user must first dial the
station (extension) number connected to the MLC-24’s
“control line.” The MLC-24 will answer with a steady
tone. The command codes can then be entered as
shown in the table to the right.
Signaling the MLC-24...
1. ...to turn lamp OFF at station xy*
2. ...to turn lamp ON at station xy*
3. ...to flash a lamp at station xy*
4. ...to fast flash a lamp at station xy*
5. ...to turn all lamps OFF
Enter Digits
1 + xy*
2 + xy*
3 + xy*
4 + xy*
1 - 4 + 99
When the MLC-24 is located in a remote facility, the voice mail system or user must call the telephone number of the
phone line connected to the “control line” of the MLC-24 (J2 Pins 25, 50). The MLC-24 will answer with a steady
tone. The command codes can then be entered as shown in the table.

B. Off Premise Operation

In applications where a ringing extension is not available, the MLC-24 can be programmed to provide talk battery for
direct connection to an unused trunk input, a standard DTMF phone or the voice mail “dispatch” or “out-call” port, if
compatible.
In voice mail applications the “dispatch” or “out-call” feature is used to call the extension assigned to the MLC-24, which
answers and provides a 500 Hz tone. The voice mail system then sends a three digit DTMF code that specifies the
status of an individual lamp. For example, a Touch Tone code of “1, 24” would cause lamp 24 to be off, a “2, 24” would
cause it to be on steady, a “3, 24” would cause it to flash and a “4, 24” would cause it to fast flash. When the three digit
code is complete, the MLC-24 hangs up. The 3 digit code can also be entered manually from any Touch Tone phone.
One MLC-24 controller can serve 24 different station lamps, plus up to three 24 line status displays (LM-24D or LM-
12W) for the receptionist(s). Up to four MLC-24’s can be installed on a single extension or line.
* xy refers to numbers 1 - 96
2. With switch positions 2 and 3 in the “off” position and 1 and 4 in the “on” position, the installer can generate a test
pattern that will aid in the installation. The MLC-24 will turn the lamps on one at a time, then turn them all off.
This will continue until the switches are placed back into position for normal operation.