User's Manual

SmartAlert 8214/8205 Programming/Installation Guide 320124E Page 15
Appendix A - Telephone Interconnect Specifications
Telephone Interfacing
Phone Line Interface – The SmartAlert transmitter with telephone will accept
input from end-to-end (line level) telephone circuits. Selector or trunk level input
is not possible. The phones and phone system must be capable of DTMF and
provide a Bell standard ringing voltage.
PABX Interface – The PABX (Private Automated Branch Exchange) must pass
DTMF tones, and Ringing Voltage, for the SmartAlert transmitter with telephone
to work. A simple test can be used to see if DTMF tones are passed through the
telephone system. Dial a phone extension and depress any of the keys on the
phone pad. If the party you called can hear tones, then the system does pass
DTMF. Because many of the newer PABX’s are digital systems, they may not
pass DTMF. In this situation, the customer must install a separate DTMF
capable end-to-end phone line for the SmartAlert transmitter with telephone.
Special feature phone consoles may not use DTMF signaling and you can also
use the test described above to test the phone consoles.
Key System – Some customers may not have a PBX, but may have multiple
telephone lines, which are connected to numerous phone sets with push buttons
to activate “pick up”. In this situation, a separate telephone line should be
dedicated to the SmartAlert transmitter with telephone and users would dial a 7-
digit phone number to access the SmartAlert transmitter with telephone.
Telephone Interconnect Description
The SmartAlert transmitter with telephone’s interface is that of a very basic ‘Line
Level’ hook-up which operates in the following manner:
• The telephone system supplies ‘battery’ voltage across Tip and Ring. When
measured from ground ‘-48’ volts will be seen on Ring while ‘0’ volts (ground),
will be seen on Tip.
• When someone picks up a phone and enters the phone number to the
SmartAlert transmitter with telephone, the telephone system applies an
interrupted ‘Ringing’ voltage (two seconds ring, four seconds rest) across Tip
and Ring. Ringing voltage is an AC signal, which is usually around 105 volts
rms.
• The SmartAlert transmitter with telephone's module detects the ringing and
recognizes it as a request for seizure. The encoder’s telephone module goes
off hook, energizes a relay, and puts a low impedance closure across Tip and
Ring, back to the telephone system.