Calculating Your DTMF Receiver Needs
You can use the following formula to determine how many DTMF receivers you must install in your system.
(Simultaneous Dialing Telephones) - (1 Telephone Supported By Services Board) = Total DTMF Receivers needed
If you are not sure how many telephones will dial at the same time in your system, you can use the following
typical system averages and formula to arrive at a usable estimate.
A typical telephone system, experiences the following call traffic percentages. Your system may be similar.
•
Light Call Traffic = up to 15 percent of the telephones dial simultaneously
•
Moderate Call Traffic = up to 20 percent of the telephones dial simultaneously
•
Heavy Call Traffic = up to 30 percent of the telephones dial simultaneously
Using the above estimates, calculate the number of IST telephones that will dial at the same time.
(Percent Of Simultaneous Dialing) x (Installed IST Telephones) = (Simultaneous Dialing Telephones)
Complying With Underwriters Laboratories Regulations
Per The Underwriters Laboratories regulation, be aware of the following precautions when installing telephone
equipment that is to be directly connected to the telephone company network:
•
Never install telephone wiring during a lightning storm.
•
Never install telephone jacks in wet locations unless the jack is specifically designed for wet locations.
•
Never touch uninsulated telephone wires or terminals unless the telephone line has been disconnected at the
network interface.
•
Use caution when installing or modifying telephone lines.
•
Avoid using a telephone (other than a cordless type) during an electrical storm—there may be a remote risk of
electrical shock from lightning.
•
Do not use the telephone to report a gas leak in the vicinity of the leak.
Installing The IST Board – 3
Installing The IST Station Board
IMI89–268
Typical Auxiliary Board
DTMF Receiver Card Mounting Locations
dtmf_crd.cdr
4-40 x 3/8 Machine Screw
Option Card
#4 x 1/2 Standoff
#4 Star Washer
Auxiliary Board
#4 Nut
Locating The DTMF Receiver Cards
